CN102680027B - Method for calculating displacement and discharging time in dynamical precipitation process of pressure-load fully penetrating well or well group - Google Patents

Abstract

The invention discloses a method for calculating displacement and discharging time in a dynamical precipitation process of a pressure-load fully penetrating well or a well group. The method comprises the following steps of: integrating a precipitation area on basis of a given formula for calculating the displacement per day when a water level is remained and stabilized in the precipitation process of the pressure-load fully penetrating well or the well group; and establishing a specific calculation method of the displacement and the discharging time in a process that an underground water level of the pressure-load fully penetrating well or the well group is changed from an original water level to a target water level. According to the method provided by the invention, the current condition that the displacement calculation in a water level variation stage depends on the experience for a long time when the pressure-load fully penetrating well or the well group is designed is changed, so that the calculation and the dynamic control of the displacement of the full precipitation process of the pressure-load fully penetrating well or the well group in engineering construction can be realized.

Description

The computing method of water discharge and water discharge time in the dynamic Precipitation Process of a kind of pressure-bearing whole well or gang of wells

Technical field

The present invention relates to a kind of computing method that are applicable to engineering construction dewatering and drainage amount, be specifically related to the computing method of water discharge and water discharge time in the dynamic Precipitation Process of a kind of pressure-bearing whole well or gang of wells.

Background technology

The object of base pit dewatering is underground water table to be reduced to below a certain depth requirements, can meet foundation pit structure and apply under the condition of anhydrous interference, thereby reduce difficulty of construction, and ensure to the full extent the safety of excavation of foundation pit and structure construction.

At present both at home and abroad the water discharge of every day has carried out a large amount of research when maintaining a certain fixed level in Precipitation Process.Theoretical side, for stable in confined aquifer, unsteady state flow through porous medium motion, has proposed the corresponding flow theory of underground water, has derived corresponding water discharge computing formula.For disturbing gang of wells base pit dewatering problem, also there is researcher to work out relative program, to foundation ditch and underground water table real-time estimate around.Numerical computation method is also widely used in engineering dewatering calculates, and is considering inside and outside various boundary, hole, whether have on the basis of hydraulic connection etc., can study the decline process in time of artesian groundwater water level in precipitation.Some scholars consider taking the pumping test data in precipitation test as basis, the perviousness of underground water under different condition in research ground; Study underground water table, aquifer yield, coverage and the variation relation along with the time thereof of individual well well point and single well point under the different well points degree of depth, different external interference effect, so that the conventional typical calculation formula of well-points dewatering is supplemented and to be improved.But the quantity of precipitation that declines or go up every day in stage for engineering construction pressure-bearing whole well or gang of wells Precipitation Process middle water level, at present both at home and abroad not relevant computing method also, in application, on many bases of taking out in examination according to field technician's experience, constantly adjust at the scene, final definite concrete water discharge, all can produce certain impact to the aspect such as duration, cost of engineering.

On the whole, engineering construction pressure-bearing whole well or gang of wells Precipitation Process middle water level decline or the quantity of precipitation of ging up every day in stage more than depend on engineering technical personnel's experience, cannot meet the requirement of engineering construction precipitation.

Therefore the computing method of, developing water discharge and water discharge time in a kind of novel pressure-bearing whole well or the dynamic Precipitation Process of gang of wells are for being badly in need of.

Summary of the invention

General technical problem to be solved by this invention is to overcome that existing pressure-bearing whole well or gang of wells precipitation dynamic process middle water level decline or the calculating of the stage water discharge that gos up depends on the present situation of experience for a long time, provides a kind of pressure-bearing whole well or gang of wells precipitation dynamic process middle water level to decline or the computing method of go up stage water discharge and water discharge time.

In order to realize above-mentioned technical purpose, technical scheme of the present invention is, the computing method of water discharge and water discharge time in the dynamic Precipitation Process of a kind of pressure-bearing whole well or gang of wells, for pressure-bearing whole well, are calculated water level in dewatering well from S by following formula ₁decline or go up to S ₂the total displacement Q of required increase or minimizing in process:

$Q={\∫}_{S_2}^{S_1}2.73\frac{\mathrm{kM}}{\lg \frac{R}{r_w}}\mathrm{SdS}$

Wherein K is AQUIFER HYDRAULIC, and M is confined aquifer thickness, and S is design water level drawdown, and R is Rainfall Influence radius, r _wfor dewatering well radius;

For pressure-bearing whole well group, calculate water level in dewatering well from S by following formula ₁decline or go up to S ₂the total displacement Q of required increase or minimizing in process:

$Q={\∫}_{S_2}^{S_1}\frac{2.73\mathrm{KMS}}{\lg [(R+r_0)/r_0]}\mathrm{dS}$

Wherein K is AQUIFER HYDRAULIC, and M is confined aquifer thickness, and S is design water level drawdown, and R is Rainfall Influence radius, r ₀for foundation ditch conversion radius.

The computing method of water discharge and water discharge time in described a kind of pressure-bearing whole well or the dynamic Precipitation Process of gang of wells, described AQUIFER HYDRAULIC K, if water-bearing zone is multilayer and vicinity, the desirable weighted mean value of K, computing method are K=∑ (K _ih _i)/∑ h _i, wherein K _ifor the infiltration coefficient in each water-bearing zone, h _ifor the thickness in each water-bearing zone.

The computing method of water discharge and water discharge time in described a kind of pressure-bearing whole well or the dynamic Precipitation Process of gang of wells, the computing method of described confined aquifer thickness M are: M=∑ h _i, wherein h _ifor the thickness in each water-bearing zone.

The computing method of water discharge and water discharge time in described a kind of pressure-bearing whole well or the dynamic Precipitation Process of gang of wells, described Rainfall Influence radius R can obtain by steady flow water pumping experiment, in the time not having condition to carry out steady flow water pumping experiment, also can be by formula calculate.

The computing method of water discharge and water discharge time in described a kind of pressure-bearing whole well or the dynamic Precipitation Process of gang of wells, described foundation ditch conversion radius r ₀computing method be: when foundation ditch is carried out to precipitation, if the position of periphery dewatering well also not design, calculate by foundation ditch area, wherein F is foundation ditch area; If foundation ditch periphery dewatering well is arranged, preferentially calculate by the position of well, wherein n is well point quantity.

The computing method of water discharge and water discharge time in described a kind of pressure-bearing whole well or the dynamic Precipitation Process of gang of wells, according to the water level in tried to achieve dewatering well from S ₁decline or go up to S ₂the total displacement Q of required increase or minimizing in process, total displacement Q is dispensed to the every day of carrying out in water level decline or rise stages period, the method that the water discharge of pressure-bearing partially penetrating well or gang of wells every day superposes then and while maintaining fixed level is calculated the water discharge Q of every day in precipitation dynamic process _m1, required Q _m1computing formula be:

$Q_{m1}=Q_{S2}+\frac{Q}{m}$

Wherein Q is that the interior water level of well is by S ₁decline or go up to S ₂the total displacement of required increase or minimizing, m is total number of days of water level decline or rise stages period, stablize drawdown S for maintaining ₂time every day needed water discharge, in the time being individual well:

In the time being gang of wells: $Q_{S_2}=\frac{2.73\mathrm{KMS}}{\lg [(R+r_0)/r_0]}.$

The computing method of water discharge and water discharge time in described a kind of pressure-bearing whole well or the dynamic Precipitation Process of gang of wells, according to the water level in tried to achieve dewatering well from S ₁decline or go up to S ₂the total displacement Q of required increase or minimizing in process, by dewatering well arrangement pitch and location positioning and make the dewatering well drainability Q of every day _nin definite situation, by calculating drainability Q _nwater discharge while maintaining fixed level with every day difference and determine with the method for the ratio of total displacement Q the total number of days m that is down to the needed cycle of target water level, the computing formula of required m is:

$m=\frac{Q}{Q_n-Q_{S_2}}$

Wherein Q _nfor the dewatering well drainability of every day, stablize drawdown S for maintaining ₂time every day needed water discharge, Q be in well water level by S ₁decline or go up to S ₂the total displacement of required increase or minimizing.

The computing method of water discharge and water discharge time in described a kind of pressure-bearing whole well or the dynamic Precipitation Process of gang of wells, the unit of AQUIFER HYDRAULIC K is rice every day, the unit of confined aquifer thickness M is rice, the unit of design water level drawdown S is rice, the unit of Rainfall Influence radius R is rice, dewatering well radius r _wunit be rice, foundation ditch conversion radius r ₀unit be rice, the coefficient of permeability K in each water-bearing zone _iunit be rice an every day, the thickness h in each water-bearing zone _iunit be rice, the unit of foundation ditch area F be square metre that the interior water level of well is by S ₁decline or go up to S ₂the unit of the total displacement Q of required increase or minimizing is cubic meter, maintains and stablizes drawdown S ₂time every day needed water discharge unit be cubic meter, the drainability Q of dewatering well every day _nunit be cubic meter, maintain and stablize drawdown S ₂time every day needed water discharge unit be cubic meter, the water discharge Q of every day in precipitation dynamic process _m1unit be cubic meter.

Technique effect of the present invention is, traditional foundation ditch pressure-bearing whole well or gang of wells precipitation computing method can only obtain maintaining a certain fixed level needed water discharge every day, and to water level decline and rise change procedure in every day water discharge and be down to needed time of target water level and lack research.The present invention can calculate the increasing water discharge in the stability maintenance water yield and the Precipitation Process of each water level in pressure-bearing whole well or gang of wells Precipitation Process in good time, grasp accordingly the multidate information of precipitation, and be down to the needed time of target water level by determining that the well number of participation work and the layout of dewatering well are determined, and then reach pressure-bearing whole well or gang of wells precipitation overall process are dynamically controlled.

Below in conjunction with accompanying drawing, the invention will be further described.

Brief description of the drawings

Fig. 1 is single sinking funnel curve synoptic diagram of the present invention

In figure: 1---dewatering well; 2---initial water level oozes and falls funnel curve; 3---target water level is oozed and is fallen funnel curve; 4---foundation ditch; 5---water-resisting layer; 6---precipitation region; 7---S ₂the drawdown place radius of influence; 8---S ₁the drawdown place radius of influence; 9---drawdown S ₁; 10---drawdown S ₂; 11---confined aquifer thickness; 12---precipitation infinitesimal dS.

Embodiment

(1) computing method of water discharge and water discharge time in individual well water level decline process

First get individual well analysis, as shown in Figure 1, after precipitation, form precipitation funnel curve at the periphery of well, arrive in this precipitation region because the surrounding of dewatering well 1 constantly has the recharge of ground water, for ensureing that in well, water level maintains a certain fixed level S ₁, need to maintain stable water discharge Q (S every day ₁), initial water level now oozes and falls funnel curve 2 for X ₁, when further the water level in well being down to S ₂time, form target water level and ooze and fall funnel curve 3 for X ₂, now need every day at original stable water discharge Q (S ₁) basis on add the water discharge in well, also increase precipitation funnel curve X ₁and X ₂between water discharge.

As shown in Figure 1, get small drawdown dS and analyze, in the time that precipitation depth dS is tending towards infinitely small, can think precipitation funnel X ₁on vertical hopper direction of a curve, evenly expand dS, precipitation funnel curve X ₁and X ₂between water discharge can approximate representation be:

dQ(S)＝Q(S ₁)·dS (1)

Thus, the water level in dewatering well is from S ₁be down to S ₂the water discharge of required increase can be expressed as:

$Q={\∫}_{S_2}^{S_1}Q\left(S\right)\·\mathrm{dS}---\left(2\right)$

In formula: Q (S) is interior for maintaining a certain fixed level needed water discharge every day for dewatering well, and it is the function of precipitation depth S in well, changes along with the variation of precipitation depth.Existing a large amount of document is studied this both at home and abroad at present, and the expression formula that pressure-bearing whole well water discharge calculates can directly be applied.

For pressure-bearing whole well, the water level in dewatering well is from S ₁be down to S ₂the water discharge expression formula of required increase is:

$Q={\∫}_{S_2}^{S_1}2.73\frac{\mathrm{kM}}{\lg \frac{R}{r_w}}\mathrm{SdS}---\left(3\right)$

Wherein K is AQUIFER HYDRAULIC, and unit is rice every day, if water-bearing zone is multilayer and vicinity, and the desirable weighted mean value of K, computing method are K=∑ (K _ih _i)/∑ h _i, wherein K _ifor the infiltration coefficient in each water-bearing zone, unit is rice every day, h _ifor the thickness in each water-bearing zone, unit is rice, and M is confined aquifer thickness, and unit is rice, and computing method are: M=∑ h _i, wherein h _ifor the thickness in each water-bearing zone, unit is rice, S is design water level drawdown, unit is rice, R is Rainfall Influence radius, unit is rice, can obtain by steady flow water pumping experiment, steady flow water pumping experiment is application steady flow theoretical analysis Pumping Test Data, draws at any time the curves such as flow-drawdown, and obtain accordingly the radius of influence in water-bearing zone, in test, must reach flow and drawdown is relatively stable, and determine that according to water-bearing zone lithology to need continuity certain long-time, just can stop, in the time not having condition to carry out steady flow water pumping experiment, also can be by formula calculate r _wfor dewatering well radius, unit is rice.

While calculating with above formula, can directly carry out Integration Solving, if direct integral calculates while being difficult to solve, can adopt the method for numerical integration to calculate.

More than calculate be maintain fixed level in well taking every day water discharge as basis, calculate should be water level in dewatering well in one day from S ₁be down to S ₂needed water discharge, for Practical Project, can not within one day, just water level can be down to desired value, generally need within a period of time, complete, now just need to maintain on the basis of quantity of precipitation of fixed level in every day, the water discharge of increase is dispensed to every day, supposes in m days in well that water level is by S ₁be down to S ₂, in water level decline process, the water discharge of every day can calculate with following formula.

$Q_{m1}=Q_{S2}+\frac{Q}{m}---\left(4\right)$

In formula: Q _m1for the water discharge of every day water level decline stage, unit is cubic meter, stablize drawdown S for maintaining ₂time every day needed water discharge, in the time being individual well:

In the time being gang of wells: unit is cubic meter, and Q is that the interior water level of well is by S ₁be down to S ₂the total displacement of required increase or minimizing, unit is cubic meter, m is precipitation number of days.

Under the definite condition of the drainability of dewatering well every day, underground water table declines or gos up to the required time of desired value and can calculate with following formula.

$m=\frac{Q}{Q_n-Q_{S_2}}---\left(5\right)$

In formula: Q _nfor the dewatering well drainability of every day, unit is cubic meter, stablize drawdown S for maintaining ₂time every day needed water discharge, unit is cubic meter, Q be in well water level by S ₁decline or go up to S ₂the total displacement of required increase or minimizing, unit is cubic meter, total number of days that m is cycle in precipitation.

(2) computing method of water discharge and water discharge time in the outer gang of wells water level decline process in hole

Water discharge for Metro station excavation gang of wells in water level decline process, can calculate by the identical method of individual well water discharge, and the quantity of precipitation expression formula of pressure-bearing whole well gang of wells in water level decline process is as follows thus.

Water level in pressure-bearing whole well is from S ₁be down to S ₂the water discharge expression formula of required increase is:

$Q={\∫}_{S_2}^{S_1}\frac{2.73\mathrm{KMS}}{\lg [(R+r_0)/r_0]}\mathrm{dS}---\left(6\right)$

Wherein K is AQUIFER HYDRAULIC, and unit is rice every day, and M is confined aquifer thickness, and unit is rice, and S is design water level drawdown, and unit is rice, and R is Rainfall Influence radius, and unit is rice, r ₀for foundation ditch conversion radius, unit is rice, and computing method are: when foundation ditch is carried out to precipitation, if the position of periphery dewatering well is not also designed, calculate by foundation ditch area, wherein F is foundation ditch area, and unit is square metre; If foundation ditch periphery dewatering well is arranged, preferentially calculate by the position of well, wherein n is well point quantity.L is foundation ditch length, and unit is rice.

In like manner, more than calculate be also water level in precipitation foundation ditch 4 in one day from S ₁be down to S ₂needed water discharge for Practical Project, need to be down to desired value by water level equally within a period of time, in m days the water level in foundation ditch by S ₁be down to S ₂time, in water level decline process, the same available formula of the water discharge of every day (4) is calculated.

In Practical Project, if determined precipitation time, can determine according to the water discharge of the every day calculating quantity and the concrete arrangement requirement of dewatering well, if determined quantity and the arrangement of dewatering well, can calculate underground water table is down to the needed time of desired value according to (5) formula according to the water discharge calculating, carry out accordingly the design of engineering construction tissue.

(3) computing method of water discharge and water discharge time in the outer gang of wells rising of groundwater level process in hole

The rise of underground water table is the inverse process of precipitation, and the water yield alimentation facies outside precipitation funnel is same, and thus, water level is by S ₂go back up to S ₁the water discharge of required minimizing can be expressed as:

$Q_j={\∫}_{S_2}^{S_1}Q\left(S\right)\·\mathrm{dS}---\left(7\right)$

In formula: Q (S) meaning is the same, for maintaining a certain fixed level needed water discharge every day.

In like manner, above calculating is also the water discharge that maintains fixed level in well taking every day as basis, calculate be water level in dewatering well in one day by S ₂go back up to S ₁the water discharge of required minimizing, for Practical Project, also can not one day within by rising of groundwater level desired value, now just need to maintain on the basis of quantity of precipitation of fixed level in every day, the water discharge of minimizing is dispensed to every day, supposes in m days in well that water level is by S ₂go back up to S ₁, in rising of groundwater level process, the water discharge of every day can calculate with following formula.

$Q_{m2}=Q_{S1}+\frac{Q_j}{m}---\left(8\right)$

In formula: Q _m2for the water discharge of every day in rising of groundwater level stage, unit is cubic meter, stablize drawdown S for maintaining ₁time every day needed water discharge, unit be cubic meter, Q _jfor water level in well is by S ₂go up to S ₁the total displacement of required minimizing, unit is cubic meter, m is precipitation number of days.

The in the situation that of dewatering well arrangement pitch and location positioning, the drainability of dewatering well every day determines also and just determined, corresponding precipitation time calculates according to (5) formula equally.

Claims (6)

1. computing method for water discharge and water discharge time in the dynamic Precipitation Process of pressure-bearing whole well or gang of wells, is characterized in that, for pressure-bearing whole well, calculate water level in dewatering well from S by following formula ₁decline or go up to S ₂the total displacement Q of required increase or minimizing in process:

Wherein K is AQUIFER HYDRAULIC, and M is confined aquifer thickness, and S is design water level drawdown, and R is Rainfall Influence radius, r _wfor dewatering well radius;

For pressure-bearing whole well group, calculate water level in dewatering well from S by following formula ₁decline or go up to S ₂the total displacement Q of required increase or minimizing in process:

Wherein K is AQUIFER HYDRAULIC, and M is confined aquifer thickness, and S is design water level drawdown, and R is Rainfall Influence radius, r ₀for foundation ditch conversion radius;

According to the water level in tried to achieve dewatering well from S ₁decline or go up to S ₂the total displacement Q of required increase or minimizing in process, by dewatering well arrangement pitch and location positioning and make the dewatering well drainability Q of every day _nin definite situation, by calculating drainability Q _nwater discharge while maintaining fixed level with every day difference and determine with the method for the ratio of total displacement Q the total number of days m that is down to the needed cycle of target water level, the computing formula of required m is:

Wherein Q _nfor the dewatering well drainability of every day, Q is that the interior water level of well is by S ₁decline or go up to S ₂the total displacement of required increase or minimizing, stablize drawdown S for maintaining ₂time every day needed water discharge, in the time being individual well:

In the time being gang of wells:

2. the computing method of water discharge and water discharge time in a kind of pressure-bearing whole well according to claim 1 or the dynamic Precipitation Process of gang of wells, it is characterized in that, described AQUIFER HYDRAULIC K, if water-bearing zone is multilayer and vicinity, the desirable weighted mean value of K, computing method are K=∑ (K _ih _i)/∑ h _i, wherein K _ifor the infiltration coefficient in each water-bearing zone, h _ifor the thickness in each water-bearing zone.

3. the computing method of water discharge and water discharge time in a kind of pressure-bearing whole well according to claim 1 or the dynamic Precipitation Process of gang of wells, is characterized in that, the computing method of described confined aquifer thickness M are: M=∑ h _i, wherein h _ifor the thickness in each water-bearing zone.

4. the computing method of water discharge and water discharge time in a kind of pressure-bearing whole well according to claim 1 or the dynamic Precipitation Process of gang of wells, it is characterized in that, described Rainfall Influence radius R obtains by steady flow water pumping experiment, in the time not having condition to carry out steady flow water pumping experiment, by formula calculate.

5. the computing method of water discharge and water discharge time in a kind of pressure-bearing whole well according to claim 1 or the dynamic Precipitation Process of gang of wells, is characterized in that described foundation ditch conversion radius r ₀computing method be: when foundation ditch is carried out to precipitation, if the position of periphery dewatering well also not design, calculate by foundation ditch area, wherein F is foundation ditch area; If foundation ditch periphery dewatering well is arranged, preferentially calculate by the position of well, wherein n is well point quantity.

6. the computing method of water discharge and water discharge time in a kind of pressure-bearing whole well according to claim 1 or the dynamic Precipitation Process of gang of wells, is characterized in that, according to the water level in tried to achieve dewatering well from S ₁decline or go up to S ₂the total displacement Q of required increase or minimizing in process, total displacement Q is dispensed to the every day of carrying out in water level decline or rise stages period, the method that the water discharge of pressure-bearing partially penetrating well or gang of wells every day superposes then and while maintaining fixed level is calculated the water discharge Q of every day in precipitation dynamic process _m1, required Q _m1computing formula be:

Wherein Q is that the interior water level of well is by S ₁decline or go up to S ₂the total displacement of required increase or minimizing, m is total number of days of water level decline or rise stages period, stablize drawdown S for maintaining ₂time every day needed water discharge, in the time being individual well:

In the time being gang of wells: