CN104963346A - Support construction method for deep foundation pit in complex geological condition - Google Patents

Abstract

The invention particularly relates to a support construction method for a deep foundation pit in a complex geological condition. The support construction method is characterized by comprising the following steps that 1, trench wall soil is reinforced through a three-axis cement mixing pile; 2, a guide wall of a continuous wall is constructed; 3, trenching construction is conducted after a trench section is divided, and a hydraulic bucket trenching machine is used for grabbing out a soft soil layer on the upper portion in the trench section; 4, a rotary drilling rig conducts rotary excavation and smashing on a rock stratum and drills out drilling slag; 5, a moderately weathered rock stratum and a slightly weathered rock stratum are broken through a percussion drill; 6, the bottom of the hydraulic bucket trenching machine is cleaned; 7, two layers of geotechnical cloth are laid on the two large faces of a reinforcement cages at the same cave depth respectively; 8, a guide pipe is placed downwards into the deep foundation pit, and concrete is poured. By the adoption of the support construction method, soil on the trench walls on the two sides of the foundation pit is reinforced, and the trench wall stability is guaranteed when various machines operate for a long time in the trench section and generate disturbance in the trench section trenching construction process; the efficiency of entering rock of the continuous wall is improved, concrete is effectively saved, and the waste of concrete is reduced.

Description

The Extra-Deep Foundation Pit construction method of complicated geological

Technical field

The present invention relates to civil engineering foundation construction field, specifically a kind of Extra-Deep Foundation Pit construction method of complicated geological.

Background technology

The situation of geological condition complexity is often met when Urban Building Construction, as stratum is from top to bottom respectively: miscellaneous fill, plain fill, old city miscellaneous fill, sandy silt, loam, clay (expansive soil), completely decomposed calcareous shale, severely-weathered calcareous shale, middle weathering and gentle breeze calcareous shale, also there is solution cavity in local.

Wherein, old city miscellaneous fill is based on silty clay, mucky soil, silt, local is containing peat and organic matter, containing brick and tile fragment etc., local is block stone, generally presents plastic ~ soft shape of moulding, soil property is extremely uneven, this soil layer is large on structure construction impact, must adopt suitable method, the engineering measure such as strengthening supporting, waterproof.Swell deformation of expansive soil encountered with water, dehydration shrinkage, easily causes side slope craze and transfiguration to destroy to excavation of foundation pit, produces squeeze and destroy etc. to preventive works such as reinforcings; Decomposed rock: formation composition is uneven, after construction disturbance or infiltration, intensity obviously reduces, and is unfavorable for foundation ditch adjoining rock stability.The size of solution cavity exists uncertain, if do not taken measures will to cause significant wastage to the concrete of building when going along with sb. to guard him construction.

Summary of the invention

The object of the invention is to, improve the efficiency of construction of Extra-Deep Foundation Pit under complex geological condition and reduce construction cost.

In order to achieve the above object, the present invention is achieved in that

The deep foundation ditch of complicated geological go along with sb. to guard him a construction method, comprise the steps;

Step 1, in the diaphragm wall both sides of pressing close to draft construction, adopt triaxial cement mixing pile to carry out reinforcing operation to its cell wall soil body, reinforcement depth is until at least 0.5m below face, rock stratum;

Step 2, perform diaphragm wall lead wall;

Step 3, according to designing requirement, carry out trenching construction by after groove section framing, with hydraulic grab bucket grooving machine, soil layer soft for groove section internal upper part caught, until rock stratum grab motionless till;

Step 4, change rotary drilling rig, rock stratum revolved and digs fragmentation, get out boring mud, until in harder, micro-weathered rock formation;

Step 5, change percussive drill, utilize the large tup of percussive drill, by middle weathering, gentle breeze crushing rock formation, until projected depth;

Step 6, change grab type groover and carry out the end clearly, rock disintegrating slag is all pulled out, until sediment thickness etc. meet design requirement;

Step 7, install reinforcing cage, survey out the position and the degree of depth that have solution cavity according to geologic information, paste the work cloth that spreads a layer of clay respectively, for block solution cavity in two large faces of reinforcing cage with cavern depth place;

Step 8, transfer conduit and concreting, complete this groove segment construction of diaphragm wall, proceed to the construction of lower width, until whole foundation ditch diaphragm wall completes.

The Extra-Deep Foundation Pit construction method of described complicated geological; When geology has soft stratum, after top soft soil horizon being excavated with grab chute forming machine, bore a hole respectively in the bucket tooth position of grab bucket both sides and then carry out muck construction; Within the scope of grab bucket bucket tooth, increase drilling hole amount when rock stratum is harder, make total hole count be not less than 3.

The Extra-Deep Foundation Pit construction method of described complicated geological, when geology top layer has weathered rock formation, need bottom triaxial cement mixing pile to enter weathered rock formation, concrete implementation step comprises:

Step 1.1, the both sides shaft of three axes agitating pile machine to be removed, only retain an intermediate agitation axle and be used for drawing hole and break rock;

Step 1.2, reserve agitation pile stake position, carry out drawing hole and break rock construction;

Step 1.3, draw hole break rock adopt construct every 1 hole;

Step 1.4, all agitation pile are drawn hole and are broken after rock terminates and reinstalled other two shafts, carry out cell wall strengthening construction.

This construction method, to foundation ditch both sides cell wall soil stabilization, ensure that the slurry trench stability of all kinds of machinery for a long time in groove section during operation disturbance in groove section trenching construction; Its speed is faster than Double shaft stirring pile driving construction speed, verticality good, overlap joint stagnant water effect is good, construction depth is large as reinforcing to adopt three axes agitating pile; And cell wall is reinforced and must be embedded rock stratum certain depth, prevent because groove rapid lapse of time to come to nothing the accident of the sliding groove inlet section of fracture by causing agitation pile after collapsing for the soil body supported bottom agitation pile after mechanical disturbance; By mechanical modification, by the agitation pile of rock originally cannot be entered, achieve into rock function, improve agitation pile performance, and decrease machinery expenses input; The efficiency making diaphragm wall enter rock improves, cost reduces; Concrete has effectively been saved in the use of geotextiles, decreases concrete waste.

Detailed description of the invention

The present invention is further illustrated below by way of specific embodiment.

The deep foundation ditch of complicated geological go along with sb. to guard him a construction method, comprise the steps;

Step 1, in the diaphragm wall both sides of pressing close to draft construction, adopt triaxial cement mixing pile to carry out reinforcing operation to its cell wall soil body, reinforcement depth is until at least 0.5m below face, rock stratum;

Step 2, perform diaphragm wall lead wall;

Step 3, according to designing requirement, carry out trenching construction by after groove section framing, with hydraulic grab bucket grooving machine, soil layer soft for groove section internal upper part caught, until rock stratum grab motionless till;

Step 4, change rotary drilling rig, rock stratum revolved and digs fragmentation, get out boring mud, until in harder, micro-weathered rock formation;

Step 5, change percussive drill, utilize the large tup of percussive drill, by middle weathering, gentle breeze crushing rock formation, until projected depth;

Step 6, change grab type groover and carry out the end clearly, rock disintegrating slag is all pulled out, until sediment thickness etc. meet design requirement;

Step 7, install reinforcing cage, survey out the position and the degree of depth that have solution cavity according to geologic information, paste the work cloth that spreads a layer of clay respectively, for block solution cavity in two large faces of reinforcing cage with cavern depth place;

Step 8, transfer conduit and concreting, complete this groove segment construction of diaphragm wall, proceed to the construction of lower width, until whole foundation ditch diaphragm wall completes.

The Extra-Deep Foundation Pit construction method of described complicated geological; When geology has soft stratum, after top soft soil horizon being excavated with grab chute forming machine, bore a hole respectively in the bucket tooth position of grab bucket both sides and then carry out muck construction; Within the scope of grab bucket bucket tooth, increase drilling hole amount when rock stratum is harder, make total hole count be not less than 3.

The Extra-Deep Foundation Pit construction method of described complicated geological, when geology top layer has weathered rock formation, need bottom triaxial cement mixing pile to enter weathered rock formation, concrete implementation step comprises:

Step 1.1, the both sides shaft of three axes agitating pile machine to be removed, only retain an intermediate agitation axle and be used for drawing hole and break rock;

Step 1.2, reserve agitation pile stake position, carry out drawing hole and break rock construction;

Step 1.3, draw hole break rock adopt construct every 1 hole;

Step 1.4, all agitation pile are drawn hole and are broken after rock terminates and reinstalled other two shafts, carry out cell wall strengthening construction.

This construction method, to foundation ditch both sides cell wall soil stabilization, ensure that the slurry trench stability of all kinds of machinery for a long time in groove section during operation disturbance in groove section trenching construction; Its speed is faster than Double shaft stirring pile driving construction speed, verticality good, overlap joint stagnant water effect is good, construction depth is large as reinforcing to adopt three axes agitating pile; And cell wall is reinforced and must be embedded rock stratum certain depth, prevent because groove rapid lapse of time to come to nothing the accident of the sliding groove inlet section of fracture by causing agitation pile after collapsing for the soil body supported bottom agitation pile after mechanical disturbance; By mechanical modification, by the agitation pile of rock originally cannot be entered, achieve into rock function, improve agitation pile performance, and decrease machinery expenses input; The efficiency making diaphragm wall enter rock improves, cost reduces; Concrete has effectively been saved in the use of geotextiles, decreases concrete waste.

Claims (3)

1. complicated geological deep foundation ditch go along with sb. to guard him a construction method, it is characterized in that: comprise the steps;

Step 1, in the diaphragm wall both sides of pressing close to draft construction, adopt triaxial cement mixing pile to carry out reinforcing operation to its cell wall soil body, reinforcement depth is until at least 0.5m below face, rock stratum;

Step 2, perform diaphragm wall lead wall;

Step 3, according to designing requirement, carry out trenching construction by after groove section framing, with hydraulic grab bucket grooving machine, soil layer soft for groove section internal upper part caught, until rock stratum grab motionless till;

Step 4, change rotary drilling rig, rock stratum revolved and digs fragmentation, get out boring mud, until in harder, micro-weathered rock formation;

Step 5, change percussive drill, utilize the large tup of percussive drill, by middle weathering, gentle breeze crushing rock formation, until projected depth;

Step 6, change grab type groover and carry out the end clearly, rock disintegrating slag is all pulled out, until sediment thickness etc. meet design requirement;

Step 7, install reinforcing cage, survey out the position and the degree of depth that have solution cavity according to geologic information, paste the work cloth that spreads a layer of clay respectively, for block solution cavity in two large faces of reinforcing cage with cavern depth place;

Step 8, transfer conduit and concreting, complete this groove segment construction of diaphragm wall, proceed to the construction of lower width, until whole foundation ditch diaphragm wall completes.

2. the Extra-Deep Foundation Pit construction method of complicated geological according to claim 1; It is characterized in that: when geology has soft stratum, after top soft soil horizon being excavated with grab chute forming machine, bore a hole respectively in the bucket tooth position of grab bucket both sides and then carry out muck construction; Within the scope of grab bucket bucket tooth, increase drilling hole amount when rock stratum is harder, make total hole count be not less than 3.

3. the Extra-Deep Foundation Pit construction method of complicated geological according to claim 1, is characterized in that: when geology top layer has weathered rock formation, and need bottom triaxial cement mixing pile to enter weathered rock formation, concrete implementation step comprises:

Step 1.1, the both sides shaft of three axes agitating pile machine to be removed, only retain an intermediate agitation axle and be used for drawing hole and break rock;

Step 1.2, reserve agitation pile stake position, carry out drawing hole and break rock construction;

Step 1.3, draw hole break rock adopt construct every 1 hole;

Step 1.4, all agitation pile are drawn hole and are broken after rock terminates and reinstalled other two shafts, carry out cell wall strengthening construction.