CN-122013620-A - Isolated soft soil foundation widening roadbed differential settlement control structure and method

CN122013620ACN 122013620 ACN122013620 ACN 122013620ACN-122013620-A

Abstract

The invention discloses an isolated soft soil foundation widening roadbed differential settlement control structure and method, comprising a multi-stage step formed by excavating a pavement structure layer and roadbed filling soil at the shoulder side of an old roadbed filling soil, a new roadbed filling soil formed by filling the outside of the step in layers, a new pavement structure layer at the top of the new roadbed filling soil, a geogrid and a multi-foot anchoring member are paved at the top of each stage of the step, U-shaped nails of the multi-foot anchoring member are inserted into the step filling soil to be connected with the geogrid, a plurality of rows of capped piles are arranged at equal intervals at the lower part of the new roadbed filling soil to form a composite foundation, a row of lifting anti-slide piles are arranged at the inner side of the capped piles, the top of the lifting anti-slide piles are arranged at the top of the step, isolation steel sheet piles are arranged at the middle part of the top of the step and are connected through L-shaped connecting grooves, and the bottoms of the isolation steel sheet piles penetrate deep into a weak soil layer. The invention solves the additional settlement of the old road foundation caused by the filling load of the new road subgrade with the isolation widening section, and effectively controls the differential settlement of the new road subgrade and the old road subgrade.

Inventors

LI PING
SUN ZHENWEI
SONG JIANJUN
WANG WEI
JIA QUN
CHEN XIN
Qu Jinyang
DONG KAI
LI HUI
LI JUNMING

Assignees

招商局公路网络科技控股股份有限公司
招商公路京津塘工程建设管理(天津)有限公司

Dates

Publication Date: 20260512
Application Date: 20260227

Claims (9)

1. A differential settlement control structure for an isolated soft soil foundation broadens roadbed is characterized by comprising a multi-stage step formed by excavating a road surface structural layer and roadbed filling at the shoulder side of an old roadbed filling, a new roadbed filling formed by filling the outer side of a step in a layered manner, and a new road surface structural layer at the top of the new roadbed filling, wherein geogrids and multi-foot anchoring members are paved at the tops of all stages, the multi-foot anchoring members are formed by combining a plurality of U-shaped nails, the U-shaped nails of the multi-foot anchoring members are inserted into the step filling and are connected with the geogrids, the geogrids are fixed at the inner side end part of each stage of the step through the multi-foot anchoring members, a plurality of rows of capped piles are arranged at equal intervals at the lower part of the new roadbed filling, the bottoms of the capped piles penetrate through soft soil layers to reach a bearing layer, a row of raised anti-slide piles are arranged at the inner sides of the capped piles, the tops of the raised anti-slide piles are arranged at the tops of the steps, the bottoms of the raised anti-slide piles penetrate through the soft soil layers, isolation piles are arranged at the middle parts of the top stages, the isolation piles are connected with the geogrids through L-shaped connecting grooves, the isolation piles penetrate through the L-shaped connecting piles, and penetrate through the soft soil layers.
2. The isolated soft soil foundation widened roadbed differential settlement control structure of claim 1 is characterized in that the new road pavement structure layer is positioned at the top end of the top step and is connected with the excavation part of the old road pavement structure layer; Paving the new road subgrade filling soil from the old road excavation step to the edge of the new road subgrade filling soil; the geogrid is arranged at the tops of all stages of steps, and the geogrid is connected with the multi-foot anchoring member at the inner side of the tops of the steps.
3. The isolated soft soil foundation widened roadbed differential settlement control structure according to claim 1 is characterized in that the isolated steel sheet piles are arranged in the middle of a top step, the tops of the isolated steel sheet piles are positioned on the surface of the top step, the bottoms of the isolated steel sheet piles are positioned on a foundation bearing layer, the isolated steel sheet piles are continuously arranged at splicing positions of new and old roadbed along the length direction of the roadbed, and the edges of the isolated steel sheet piles are connected through L-shaped connecting grooves.
4. The isolated soft soil foundation widened roadbed differential settlement control structure according to claim 1 is characterized in that the multi-foot anchoring members are inserted into soil through grid gaps of a geogrid to fix and connect the geogrid, the multi-foot anchoring members comprise a plurality of positions, all the multi-foot anchoring members are arranged along the inner side end parts of steps of each stage to ensure anchoring connection with the end parts of the geogrid, the geogrid is fully paved and paved in layers on each stage of excavation steps and corresponding new roadbed filling, the inner side end parts of the steps are fixed through the multi-foot anchoring members, and the geogrid is fully paved to the edge parts of the new roadbed filling.
5. The isolated soft soil foundation widening subgrade differential settlement control structure as set forth in claim 1, wherein the multi-foot anchoring members comprise a plurality of multi-foot anchoring members which are continuously arranged at inner side end parts of each stage of steps at certain intervals and fix geogrid paved along the length of the roadbed, each multi-foot anchoring member comprises a U-shaped nail and a connecting piece, each multi-foot anchoring member consists of 4U-shaped nails, and tops of the U-shaped nails are connected through the connecting piece.
6. The isolated soft soil foundation widening roadbed differential settlement control structure of claim 1, wherein the capped piles are arranged at equal intervals at the bottom of the newly filled roadbed filling soil to form a capped pile composite foundation, the pile cap size is 100-120 cm, the pile cap height is 30-50 cm, the top of the capped pile is arranged at the bottom of the newly filled roadbed filling soil, and the top of the capped pile is deep into a foundation bearing layer.
7. The isolated soft soil foundation widened roadbed differential settlement control structure is characterized in that the raised anti-slide piles are continuously arranged beside the innermost capped piles along the length direction of the roadbed, the distance between the raised anti-slide piles and the capped piles is the same, the tops of the raised anti-slide piles are positioned on the top surfaces of steps at corresponding positions, the bottoms of the raised anti-slide piles penetrate into foundation bearing layers, the raised anti-slide piles are arranged on the tops of the bottommost or penultimate steps, and the caps of the raised anti-slide piles are arranged on the surfaces of the tops of the steps.
8. The construction method of the isolated soft soil foundation widening subgrade differential settlement control structure as claimed in any one of claims 1 to 7, comprising the following steps: The method comprises the steps of excavating an old road pavement structural layer and old road roadbed filling soil to the surface of a foundation layer by layer at the old road shoulder, reserving a certain width and a certain height for excavating each layer of old road roadbed filling soil to form grading steps; Pile bodies with caps are pressed in through static pressure construction, and pile caps are manufactured through in-situ pouring; The bottom or the last second stage of steps are provided with lifting anti-slide piles, pile caps at the tops of the lifting anti-slide piles are arranged on the top surfaces of the steps, the bottoms of the lifting anti-slide piles penetrate into a foundation bearing layer, pile bodies of the lifting anti-slide piles are pressed in by static pressure, and the pile caps are manufactured by cast-in-situ; After the construction of the capped piles and the lifting anti-slide piles is completed, filling new road roadbed filling soil in a layered manner, and filling and compacting the new road roadbed filling soil in a layered manner from the step at the lowest layer; paving geogrids while carrying out layered filling construction on the new road roadbed, arranging the geogrids at the inner side end part of the step, fixing the geogrids by adopting multi-foot anchoring nails, filling the new road roadbed on the paved surface of the geogrids, and compacting; After the new road subgrade is filled in layers, carrying out isolation steel sheet pile penetrating construction by adopting a static pressure or a vibrating hammer at the middle part of a top step, arranging the isolation steel sheet piles at the middle part of the top step, enabling the bottom to penetrate into a foundation bearing layer, connecting by adopting L-shaped connecting grooves, and continuously arranging along the length of the road foundation; And after the construction of the isolation steel sheet piles and the top geogrid is completed, paving a new road surface structural layer on the surface of the top geogrid.
9. The construction method of the isolated soft soil foundation widened roadbed differential settlement control structure of claim 8, wherein the construction of the isolated steel sheet pile comprises the steps of carrying out paying-off positioning pile holes on the top step surface of old roadbed filling, and carrying out pile body penetrating construction by adopting a static pressure or a vibrating hammer.

Description

Isolated soft soil foundation widening roadbed differential settlement control structure and method Technical Field The invention belongs to the technical field of civil engineering, and particularly relates to a differential settlement control structure and method for widening roadbed of an isolated soft soil foundation. Background The main mode of the existing expressway reconstruction and expansion project is to widen the existing expressway, dismantle the road surface and the auxiliary structure at the edge of the existing roadbed on the premise of keeping the road passing at one side of the existing expressway, excavate steps on the slope of the existing roadbed, process the foundation below the widened section roadbed, fill the layers of the widened section new roadbed to the design elevation after the foundation is processed, and finally construct the structure layer of the widened section road surface to finish the splicing construction of the new and old roadbed. Because the roadbed filling soil of the new and old roadbed is different from the stress history of foundation soil below the roadbed, the mechanical indexes such as strength, deformation and the like of the new and old roadbed filling soil and the foundation soil are greatly different, and the foundation treatment modes of the new and old roadbed are often different, after the roadbed is widened, the differential settlement of the new and old roadbed can be necessarily caused by prolonging the service time at any time, the occurrence of longitudinal cracks of the road surface is caused, the service function of the roadbed is reduced, and the problems such as local collapse of the roadbed even occur to serious people. In addition, because the expressway reconstruction and expansion project is mainly in coastal developed areas of China, continuous and deep soft soil layers are commonly distributed in the areas, and the differential settlement problem of the reconstruction and expansion roadbed is further aggravated by long-term settlement of soft soil foundations. Therefore, how to develop an effective soft soil foundation and widen the differential settlement control technology of the roadbed is a technical problem to be solved in the reconstruction and expansion engineering construction of the expressway in China at present. The existing differential settlement control technology for widening the roadbed is mainly divided into three types, namely, differential settlement is controlled by increasing the integrity of a spliced roadbed, steps are excavated for the existing roadbed, geogrids are arranged at splicing positions of new roadbed and old roadbed and a pavement structure layer to increase the integrity and tensile strength of the spliced roadbed and the pavement, differential settlement is controlled by a method for coordinating the foundation rigidity of the new roadbed and the old roadbed, a foundation treatment method is adjusted according to the settlement distribution of the new roadbed and the old roadbed after widening construction to coordinate the foundation rigidity of the new roadbed and the old roadbed, differential settlement is controlled by a method for reducing the additional load of the widened section roadbed, namely, the differential settlement of the new roadbed and the old roadbed is reduced by adopting light fillers such as foam concrete and the like. The existing reconstruction and expansion roadbed settlement technology has the following problems: 1. The whole performance of the new roadbed and the old roadbed can be enhanced by the steps of excavation and geogrid reinforcement, but the improvement range is limited, and when the old roadbed generates larger sedimentation under the additional load of the new roadbed of a widened section, or the new roadbed is accumulated sedimentation along with the time increase due to the occurrence of the time effect of the soft soil foundation, the differential sedimentation of the new roadbed can not be effectively controlled by the measures such as the steps of excavation, the geogrid reinforcement and the like. 2. The rigidity coordination method of the new and old roadbed foundations has higher requirements on settlement calculation of the foundations under additional loads, and because the additional load distribution of the widened roadbed is complex, and the old roadbed foundation treatment method is often different from the new roadbed, the foundation settlement distribution of the new and old roadbed is difficult to accurately estimate due to the complexity of the load distribution and the difference of foundation treatment modes, so that the foundation rigidity coordination method is difficult to obtain ideal effects. 3. The light roadbed filling method can effectively reduce additional load of the widened roadbed, reduce long-term settlement of a new roadbed and additional settlement caused by the additional load of the widened roadbed to an old roadbed, but the