CN1214395A

CN1214395A - Impact rolling to reinforce wet and depressive loess foundation and embankment

Info

Publication number: CN1214395A
Application number: CN 98117956
Authority: CN
Inventors: 杨世基
Original assignee: 杨世基
Current assignee: Beijing New Road S. T. Development Co., Ltd.
Priority date: 1998-09-09
Filing date: 1998-09-09
Publication date: 1999-04-21

Abstract

The present invention is new technology for foundation treatment and road bed reinforcement, and its key point is continuous impact rolling operation on foundation or road bed. With the increase of the number of compact rolling times, foundation or the road bed is densified from top to bottom to form a reinforced layer to meet the requirement in bearing and stability of foundation or road bed. The technical method is simple, fast, and low in engineering cost.

Description

Impact rolling to reinforce wet and depressive loess foundation and embankment

Adopting impact densifying-machine impact-rolling collapsible loess foundation and embankment is new technology, the new technology of ground processing and subgrade strengthening.

Collapsible loess is meant under native gravity pressure or native gravity pressure and additonal pressure effect, structure is destroyed and the remarkable loess of sinking that adds of generation rapidly after being subjected to water-soaked, China mainly be distributed in the Huanghe valley and to the north of the each province, grow the most with the loess of middle Yellow River regions.It is to eliminate its settlement by soaking that collapsible loess foundation is handled main purpose, has also improved bearing capacity of foundation soil simultaneously, reduces foundation deformation.Adopt the different disposal method according to settlement by soaking soil layer different-thickness and water content, commonly used have soil or cushion lime method, soil or lime soil pile method, dynamic compaction, tamping, vibro-replacement stone column method, pile foundation and a presoaking etc.Adopt impact densifying-machine on loess natural ground top layer, determine different impact-rolling passes, reach the ground processing intent according to the ground processing requirements.Roadbed after filled-up ground or the vibratory compaction is carried out impact-rolling continuously, according to the settlement amount after construction requirement that embankment is filled, can determine to reach roadbed settlement after construction rate less than 1 ‰, avoid the crushing pass of filled-up ground relative settlement, realize that Xin Xiuluji builds the road surface continuously and do not produce deformation failure, improve the subgrade and pavement bulk strength, keep the good excellent service level of surface evenness.

In recent years a kind of high-energy of the new development of South Africa Lan Pai company hits towards the formula compacting machine, in cubic metre of earth and stone compacting operation, has 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 12～15km per hour, promptly impact and grind per minute impact ground 80～100 times, be equivalent to the low frequency large amplitude shock compaction soil body, and periodically impact ground, producing strong shock wave propagates to underground deep layer, have the propagation of seismic wave characteristic, its compacting depth can increase progressively with number of rolling.Adopt the blue 25KJ impact densifying-machine of sending in South Africa, the basal surface that satisfies the need in speedway collapsible loess location, Xuanhua, Hebei to Datong District is filled out preceding impact-rolling, and utilize collapsible loess filling roadbed, in conjunction with the measure of roadbed comprehensive draining, reach and eliminate the loess foundation saturated yielding, reduce the embankment settlement amount after construction to greatest extent and avoid the roadbed differential deformation, improve loess subgrade road surface bulk strength.Show that through various test-based examinations loess foundation undisturbed soil dry density is 1.34g/cm ³, water content 8.1～12.5%, behind the impact-rolling 40 times, dry density is 1.82g/cm in the 60cm of the face of land ³, dry density is 1.70g/cm in the 110cm ³, coefficient of collapsibility is reduced to 0.0022 and 0.0011 by 0.0713 of ground undisturbed soil, has eliminated settlement by soaking.The average elasticity modulus has reached more than the 80MPa in the soil matrix 1m under the face of land, under the roadbed bottom surface in the 1m through the crushing compacting, form continuous, even, closely knit reinforcing hard formation, its technical indicator has surpassed roadbed standard on the roadbed, meets the requirement of loess foundation strengthening quality fully.Through relatively tamping and dynamic compaction are high 2～3 times than impact-rolling method processing collapsible loess foundation cost.And impact-rolling method speed of application is fast, quality good, greatly the reduction of erection time.

Claims

Impact rolling to reinforce wet and depressive loess foundation and embankment are a kind of innovative technologies of ground processing and subgrade strengthening.Its main points are to adopt the high energy impact events compacting machine, on ground or roadbed, carry out working continuously of impact-rolling,, make crushing soil layer grinding compacting from top to bottom along with the increase of impact-rolling pass, form the artificial thick-layer back-up coat of handling, reach and satisfy ground design bearing capacity and stable requirement.

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 makes the grogs dislocation; 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.The tamp standards of its shock compaction function reflection is greater than revising the Pu Shi tamp standards at present in the world, and the high energy impact events principle of work and power that is produced is identical with strong rammer, but technology is simple, construction fast evenly, saving of work and time is better than present method for processing foundation, reduces engineering cost greatly.