CN1168437A

CN1168437A - Reinforcement of mollisol foundation through impact rolling and drainage concretion

Info

Publication number: CN1168437A
Application number: CN 97103991
Authority: CN
Inventors: 杨世基
Original assignee: Individual
Current assignee: Individual
Priority date: 1997-04-14
Filing date: 1997-04-14
Publication date: 1997-12-24

Abstract

The said mollisol foundation treatment method features that the continuous impact rolling operation using impact densifying machine is combined with the vertical and horizontal drainage system set up in the mollisol foundation to speed early settlement and foundation concretion. With increasing number of impact rolling, the foundation soil is densified layer by layer from top to bottom to form artificial hard foundation shell for the needs in bearing capacity and stability of designed foundation. The said method is time saving and has low engineering cost.

Description

Reinforcement of mollisol foundation through impact rolling and drainage concretion

Impact-rolling consolidation reinforcing soft ground belongs to the applied technical field of geotechnics Soft Ground.

Weak soil is the abbreviation of weak cohesive soil.It is the cohesive soil deposit or the river drift of marine facies, lagoon facies, delta facies, drowned valley phase and the liminetic facies of the formation of later stage in the Quaternary Period, and the genus that has is deposit recently.The characteristics of weak soil are the natural moisture content height, natural void ratio is big, shear strength is low, compression coefficient is high, transmission coefficient is little.Under load action, the soft foundation supporting capacity is low, and the foundation settlement distortion is big, and differential settlement is also big, and settlement stability lasts long.Soft foundation is to run into the ground that need carry out artificial treatment at most in the engineering construction, and it is distributed in China's southeastern coast and interior ground widely.Retrieve domestic and international periodical monograph and patent documentation through consulting, and engineering practice confirms that consolidation is one of effective ways of soft soil foundation.When this method is handled natural ground.A kind of is that vertical drainage body (sand drain or plastic draining board) and sand cushion are set in ground earlier, utilize building to load gradually then from weight classification, another kind is to load precompressed before building construction in the place in advance, pore water in the soil body is discharged, ground generation sedimentation, fixed gradually, progressively improve the bearing capacity and the stability of ground.China's southeastern coast and landlocked built up or Hot work in progress, the speedway of design, Class I highway run into soft clay area, consolidation is mainly adopted in its treatment of soft foundation, and with etc. carry or surcharge preloading quickens the discharging consolidation of ground, to reach the design load requirement.In recent years the engineering that has adopts the dynamic replacement reinforcing soft ground, owing to increase vertical and horizontal drainage measure, is aided with displacement again, in the effective depth of tamping energy, makes Soft Ground reach the design load requirement, obtains effect preferably.A kind of impact compactor of the new development of existing South Africa Lan Pai company in earthwork compacting operation, has been broken through traditional mode that rolls, and has improved compaction capacity greatly.This machine grinds to roll by the impact energy size and is divided into triangle, square, pentagon, hexagon, is respectively 25KJ, 20KJ, four kinds of models of 15KJ, 10KJ, and stone roller rolls the bight and is circular-arc, by wheeled tractor traction carrying out rolling operation.Stone roller rolls heavy 12 tons, stands on ground for one jiao when impacting stone roller, when rolling forward, produces the huge impact ripple, owing to grind order bump ground, limit, it is evenly closely knit that the soil body is rolled.This machine is with the travel speed rolling operation of 12km per hour, promptly impact to grind and impact ground twice each second, be equivalent to the low frequency large amplitude shock compaction soil body, and periodically impact ground, and produce strong shock wave and propagate to underground deep layer, have the propagation of seismic wave characteristic, its compacting depth can increase progressively with number of rolling, roll about 15 times, at the compacting depth of 5m, degree of compaction can reach heavy tamp standards 90%-93%.Send company introduction according to orchid, this machine only is used for the rolling operation of the cubic metre of earth and stone abroad at present, and is also of no use in treatment of soft foundation, now just entering China and carrying out the application work of this machine in earth and rock works.Therefore, characteristic according to impact densifying-machine, vertical and horizontal drainage system in conjunction with the soft foundation setting, on ground, carry out working continuously of impact-rolling, make foundation drainage fixed, quicken sedimentation in early days, with intensity and the stability that satisfies ground, be a kind of innovative technology of Soft Ground, have broad application prospects.

During the impact compactor operation, the energy that vertical impact energy is passed to ground on the half space surface is united propagation by compressional wave (P ripple), shearing wave (S ripple) and R wave (R ripple).The particle movement of compressional wave is to belong to a kind of push-and-pull campaign that is parallel to the wave surface direction, and it increases pore water pressure, makes the grogs dislocation simultaneously; The particle movement of shearing wave causes the lateral displacement with wave surface direction quadrature; The particle movement of R wave then is made up of level and vertical component.The horizontal component of shearing wave and R wave makes between soil particle is cut, and it is closely knit that soil is obtained.Soft foundation is behind impact-rolling, and its intensity improves process and can be divided into: impact energy transforms, the enforce compression or the close soil body that shakes (comprise the gas discharge, pore water pressure rises); Liquefaction of soil mass or soil structures are destroyed (show as the weak water of hydration of soil body part and become Free water, the intensity of soil is reduced); The discharging consolidation densification (show as impact energy and make the drainage network that forms tree skill shape in the soil mass crack development soil, and be communicated with, pore water is overflowed smoothly with vertical drainage, the soil solidifying densification, intensity improves); Thixotroping recovers (making the part Free water revert to film water again, soil body densification, intensity continuation raising).Along with the increase of impact roller number of rolling, the successively fixed from top to bottom densification of ground forms and rolls the artificial thick-layer crust layer of reinforcing groundwork, to satisfy the requirement of ground design bearing capacity.

Pressure water concretion method is given in the preloading of generally adopting both at home and abroad, and its grade is carried or the time of giving pressure of overloading needs half a year to one year, simultaneously, borrows fortune a large amount of like this loading earthwork during the highway subgrade construction, and also need unload spoir and handle, time-consuming taking a lot of work, the engineering time is very long.And the impact-rolling consolidation then increases required number of rolling by the reinforcing soft ground requirement can finish at short notice, saves preloading and gives firming side, simplifies construction, and accelerating construction progress reduces engineering cost.Dynamic replacement in conjunction with the drainage system reinforcing method at home the minority engineering obtain better effects, but because strong the rammer is that the single-point high-strength impact can act on, need the displacement layer of 4-5m on the soft foundation top layer, the bad control of the uniformity of ground stabilization, exist the engineering time longer, the high and technologic limitation of cost.

Therefore, impact-rolling consolidation reinforcing soft ground, solved preloading and given pressure water concretion method and combine the deficiency of drainage system reinforcing method with dynamic replacement, and given full play to the advantage of consolidation and dynamic compaction, soft foundation can be constructed by designing requirement preferably.

At present, the present invention is just tested in Beijing-Shenyang expressway Baodi to the k57-k73 weak soil location in the Shanhai Pass, obtains effect preferably.

Claims

Independent claims are as follows:

Impact-rolling consolidation reinforcing soft ground belongs to the applied technical field of geotechnics Soft Ground.It is characterized in that adopting impact compactor, the vertical and horizontal drainage system in conjunction with soft foundation is provided with carries out working continuously of impact-rolling on ground, make foundation drainage fixed, early stage acceleration sedimentation with intensity and the stability that satisfies ground, is a kind of innovative technology of Soft Ground.

During the impact compactor operation, the energy that vertical impact energy is passed to ground on the half space surface is united propagation by compressional wave (P ripple), shearing wave (S ripple) and R wave (R ripple).The particle movement of compressional wave is to belong to a kind of push-and-pull campaign that is parallel to the wave surface direction, and it increases pore water pressure, makes the grogs dislocation simultaneously; The particle movement of shearing wave causes the lateral displacement with wave surface direction quadrature; The particle movement of R wave then is made up of level and vertical component.The horizontal component of shearing wave and R wave makes between soil particle is cut, and it is closely knit that soil is obtained.Soft foundation is behind impact-rolling, and its intensity improves process and can be divided into: impact energy transforms, the enforce compression or the close soil body that shakes (comprise the gas discharge, pore water pressure rises); Liquefaction of soil mass or soil structures are destroyed (show as the weak water of hydration of soil body part and become Free water, the intensity of soil is reduced); The discharging consolidation densification (show as impact energy and make the drainage network that forms tree skill shape in the soil mass crack development soil, and be communicated with, pore water is overflowed smoothly with vertical drainage, the soil solidifying densification, intensity improves); Thixotroping recovers (making the part Free water revert to film water again, soil body densification, intensity continuation raising).Along with the increase of impact roller number of rolling, the successively fixed from top to bottom densification of ground forms and rolls the artificial thick-layer crust layer of reinforcing groundwork, to satisfy ground design bearing capacity and stable requirement.

Pressure water concretion method is given in the preloading of generally adopting both at home and abroad, and its grade is carried or the time of giving pressure of overloading needs half a year to one year, simultaneously, borrows fortune a large amount of like this loading earthwork during the highway subgrade construction, and also need unload spoir and handle, time-consuming taking a lot of work, the engineering time is very long.And the impact-rolling consolidation then increases required number of rolling by the reinforcing soft ground requirement can finish at short notice, saves preloading and gives firming side, simplifies construction, and accelerating construction progress reduces engineering cost.Dynamic replacement in conjunction with the drainage system reinforcing method at home the minority engineering obtain better effects, but because strong the rammer is that the single-point high-strength impact can act on, need the displacement layer of 4-5m on the soft foundation top layer, the bad control of the uniformity of ground stabilization, exist the engineering time longer, the high and technologic limitation of cost.

Therefore, impact-rolling consolidation reinforcing soft ground, solved preloading and given pressure water concretion method and combine the deficiency of drainage system reinforcing method with dynamic replacement, and given full play to the advantage of consolidation and dynamic compaction, soft foundation can be constructed by designing requirement preferably.