CN102943462A - Method for improving horizontal resistance of soil horizon through carrying out piling construction on deep soft soil horizon - Google Patents

Abstract

The invention discloses a method for improving the horizontal resistance of a soil horizon through carrying out piling construction on the deep soft soil horizon. The method comprises the following steps of: drilling a dewatering well at the edge of a pile-position area; after the water level is lowered, implementing the piling of precast concrete piles by using an alternate piling method and a jumped piling method; and then, carrying out cement mixing pile construction at the midpoints of pile position center connecting lines of the precast concrete piles. The method disclosed by the invention has the advantages that a well-point dewatering and cement mixing pile driving scheme can effectively reduce the pore water pressure of soft soil and increase the foundation strength; due to the alternate piling method and the jumped piling method, two ways for pore water pressure dissipation are opened up in time and space, thereby fully guaranteeing the piling stability of precast concrete piles in deep soft soil horizons; and precast concrete piles are piled firstly and then cement mixing piles are piled, so that the integrity of cement mixing piles can be kept, the resistance of soil is increased, the horizontal displacement of pile bodies is reduced, and the requirements on construction quality and bearing capacity can be satisfied.

Description

Improve its solum horizontal drag method at the deep soft soil piling construction

Technical field

The present invention relates to a kind ofly improve its solum horizontal drag method at the deep soft soil piling construction, particularly relate to and a kind ofly beat the precast concrete pile driving construction in deep soft soil and improve its solum horizontal drag method, belong to civil engineering piling technology field.

Background technology

Described deep soft soil refers to natural void ratio e 〉=1.0 and natural moisture content greater than the fine grained soil of liquid limit, and this mount is drawn together mud, mucky soil, peat, cumulosol, the general thickness 〉=5m of its soil layer.

Day by day increasing of high-rise building and structure, precast concrete pile relies on its high-bearing capacity and stable performance to be widely used, but very few to the research proterties of precast concrete pile under horizontal loads, so that the precast concrete pile horizontal bearing capacity fails to be fully used, cause the waste of resource.Precast concrete pile horizontal bearing service behaviour is stake and native interactional problem, the drag of soil is born horizontal loading with stake week, stake produces displacement under horizontal loads, impel all soil of stake corresponding deformation to occur and produce drag, this drag has stoped further developing of stake displacement and distortion.When horizontal loading hour, drag is to be provided by the soil near ground, and the distortion of soil is mainly flexible, the all soil of stake is in the elastic compression stage, and when the increase of horizontal loading, the distortion of pile body strengthens, topsoil produces plastic yielding gradually, and make horizontal loading to the more soil layer transmission of depths, and distortion increases to the degree that can not allow or all soil of stake loses when stablizing, and Pile soil System just is tending towards destroying.

Cement mixing pile utilizes mixing pile machine that cement jet is entered the soil body and fully stirring, and cement with soil the series of physical chemical reaction occurs, and makes the weak soil scleroma, is a kind of effective form for the treatment of of soft foundation.In having beaten the ground of precast concrete pile, squeeze into again cement mixing pile, can effectively guarantee the integrality of cement mixing pile, make its more effective performance reinforce the effect of pile peripheral earth, thereby improved the horizontal resist forces of stake week soil.

Summary of the invention

The object of the present invention is to provide and a kind ofly improve its solum horizontal drag method at the deep soft soil piling construction.The precast concrete pile that the method easy construction, Using such method construction are squeezed in the deep soft soil can reach construction quality requirement and requirement for bearing capacity, and the horizontal resist forces of energy Effective Raise deep soft soil.

The present invention is implemented by following technical proposals, a kind ofly improve its solum horizontal drag method at the deep soft soil piling construction, described stake, refer to that shape of cross section is annular, square, three petal, quatrefoil shape, six petal precast concrete hollow pile or solid piles, length is 18-40 rice, and its feature comprises following process:

1) according to design, the edge in the zone, stake position that arranges at the construction field (site), by designing requirement, the dewatering well of around the place of needs piling, drilling, the well head diameter of dewatering well is 0.4-0.6 rice, well depth is 12-20 rice;

2) by dewatering well groundwater table being reduced 6-12 rice, is the true fixed pile of 2-4 rice square arrangement order in zone, stake position by adjacent two precast concrete pile position center distance, play and jump play and implement to beat precast concrete pile between adopting again.Described play refers to beat between every pile each and is spaced apart 1-2 days, and beating number of times is 2-3 time; Jump play refers to be undertaken by interval 3-5 pile body piling order at every turn;

3) beat precast concrete pile complete after, take the center of adjacent two precast concrete pile lines of centres as cement mixing pile stake position, carry out the cement mixing pile driving construction, the cement mixing pile stake directly is that 0.4-0.6 rice, cement mixing pile stake are long for 6-20 rice, squeezes into thickness of soft soil according to thick Soft Soil Layer layering situation cement mixing pile and can make respectively and pass Soft Soil Layer 0.5m or reach the requirement that standard is processed Soft Soil Layer; After the whole constructions of cement mixing pile are complete, continue precipitation 7 days to 8 days, cause cement mixing pile to solidify.

The invention has the advantages that, because dewatering well is set the technical essential 1 that the present invention adopts and technical essential 3 sets cement mixing pile, these two technology are started with from construction environment the thick-layer weak soil are improved, and can effectively reduce pore water pressure and consolidated subsoil in the weak soil.Evidence, well-points dewatering can make the groundwater table decline 5-12 rice in place, and this effect can be compensated for the pore water pressure of 50kPa-120kPa.The mud agitation pile of fetching water again after having beaten precast concrete pile can guarantee the integrality of cement mixing pile, consolidated subsoil soil, and more effective increase foundation soil horizontal resist forces reduces the horizontal movement of the generation of precast concrete pile when being subject to horizontal loading.Technical essential 2 adopt between beat and jump and beat, this has opened up two approach of pore water pressure dissipation in time and space.Technical essential 3 adopts beats first the method for beating precast concrete pile behind fetch water behind the precast concrete pile mud agitation pile and the mud agitation pile of fetching water first and compares, the method has overcome the defective that easily cement mixing pile is squeezed off owing to the inter-pile soil protuberance when beating precast concrete pile, guaranteed the integrality of cement mixing pile.In sum, well-points dewatering of the present invention and the mud agitation pile scheme of fetching water have fully guaranteed to beat precast concrete pile in the thick-layer weak soil stability, improved the horizontal resist forces of foundation soil, reduced the horizontal movement that produces when precast concrete pile is subjected to horizontal loading, can reach construction quality and require and requirement for bearing capacity.

Description of drawings

Fig. 1 arranges schematic diagram for implementing the on-the-spot part plan of the present invention.

Wherein 1-1～1-9 is precast concrete pile stake position, and 2-1～2-12 is agitation pile stake position, and 3 is dewatering well.

The specific embodiment

Below in conjunction with accompanying drawing the present invention is described as follows:

Formation distributes and engineering and geological feature of soils: top is 12 meters thick-layer weak soils, below is 6 meters silty clay, is powder soil horizon below again, can be used as the bearing stratum of pile foundation.

Project profile: planning to build 4 layers of complex building such as above-mentioned place, adopting frame construction, site area is 15 meters X50 rice.The precast concrete hollow pile is squeezed in pre-design, and pile length is 28 meters, and the stake footpath is 0.5 meter, and pile spacing is 2.5 meters.

Carry out the piling construction detailed process according to above-mentioned geological condition and engine request as follows: periphery sets dewatering well in the place, and its diameter is 0.5 meter, and the degree of depth is 12 meters.After having set dewatering well, continuous pumpage until water level descends about 6 meters, is played the construction of precast concrete hollow pile again, stake position square arrangement, and the adjacent studs center distance is 2.5 meters.The piling process is undertaken by beating and jump play, for example, first the 1-1 stake is squeezed into 1/3 long, mobile pile driving frame, again the 1-6 stake is squeezed into 1/3 long, then the 1-7 stake is squeezed into 1/3 long, by that analogy, continue to beat successively 1-2,1-9,1-4,1-3,1-8,1-5, then can be in this order or other arrangement modes to have played the residue stake long, every pile is long 28 meters by stake, beaten, beating the time interval between each is 2 days minutes for three times, and three the pile bodies jumpings in interval are beaten.Carry out afterwards the piling construction of cement mixing pile, the cement mixing pile stake directly is 0.4 meter again, adopts rectangular arranged, is positioned at the midpoint of the precast concrete hollow pile stake position line of centres that arranges, and stake is long to be 12 meters, and pile top is passed through 0.6 meter of Soft Soil Layer.After the whole constructions of cement mixing pile are complete, continue to draw water about 7 days, cement mixing pile is solidified, stop pumping.After using above-mentioned technical essential, effectively reduce land movement, for reinforcing soft ground remarkable effect is arranged, improved the horizontal resist forces of foundation soil, reduced the horizontal movement that produces when the precast concrete hollow pile is subjected to horizontal loading, can reach construction quality and require and requirement for bearing capacity.

Claims (1)

1. one kind is improved its solum horizontal drag method at the deep soft soil piling construction, described stake, refer to that shape of cross section is annular, square, three petal, quatrefoil shape, six petal precast concrete hollow pile or solid piles, length is 18-40 rice, and its feature comprises following process:

1) according to design, the edge in the zone, stake position that arranges at the construction field (site), by designing requirement, the dewatering well of around the place of needs piling, drilling, the well head diameter of dewatering well is 0.4-0.6 rice, well depth is 12-20 rice;

2) by dewatering well groundwater table is reduced 6-12 rice, be the true fixed pile of 2-4 rice square arrangement order in zone, stake position by adjacent two precast concrete pile position center distance, play and jumping play implement to beat precast concrete pile between adopting again, described play refers to same pile is squeezed at times, finishes pile driving process; Described jumping play is to play successively non-conterminous stake;

3) beat precast concrete pile complete after, take the center of adjacent two precast concrete pile lines of centres as cement mixing pile stake position, carry out the cement mixing pile driving construction, the cement mixing pile stake directly is that 0.4-0.6 rice, cement mixing pile stake are long for 6-20 rice, squeezes into thickness of soft soil according to thick Soft Soil Layer layering situation cement mixing pile and can make respectively and pass Soft Soil Layer 0.5m or reach the requirement that standard is processed Soft Soil Layer; After the whole constructions of cement mixing pile are complete, continue precipitation 7 days to 8 days, cause cement mixing pile to solidify.

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