无序采砂区勘察方法综合运用及地基处理方案

Comprehensive application of survey method and foundation treatment scheme in disordered sand mining area

采砂引起的地层结构改变和地形变化对河岸工程建设影响极大,针对采砂区空间分布、工程特性及对其处治的问题,本文在现有研究成果的基础上提出:(1)按地貌变化将采砂区分为显型、隐型2种类型;(2)通过对显型采砂区采用“地形对比法、断面法”,对隐型采砂区采用“地→空→天→地”、由“表→里”及“不同岩性→同一岩性”的综合勘察方法查明采砂区的空间分布;(3)按岩土特性将采砂区分为水坑区、巨粒土区、粗细粒土区、混合区4个区;(4)对不同岩土工程分区分别采用全换填、浅部换填、碾压3种处治方法,并对碾压处治措施提出优化方法。结果表明:这种由明及暗、由表及里、由粗至细的综合勘察方法能很好地查明整个采砂区(含显型、隐型)的空间分布,采用岩土工程分区评价、分区地基处治既有效利用了采砂区土体自身力学特性,同时减少了地基处理工程量、节约处治费用。该方法可为以后类似采砂区的工程建设提供一种可借鉴的思路。

Formation structure and topographic changes caused by sand mining have a great impact on riverbank construction.Aiming at the spatial distribution,engineering characteristics and treatment of sand mining areas,this paper proposes:(1)Sand mining can be divided into explicit type and hidden type according to geomorphic changes;(2)The spatial distribution of sand mining area is identified by using the comprehensive methods of"terrain comparison method and cross section method"for the explicit sand mining area and"ground→air→sky→earth","surface→inside"and"different lithology→same lithology"for the hidden sand mining area.(3)According to rock and soil characteristics,sand mining can be divided into four areas:Water pit area,giant grained soil area,coarse-fine grained soil area and mixed area;(4)Three treatment methods,namely deep filling,shallow filling and surface rolling,were adopted for different geotechnical engineering zones,and optimiza-tion methods were proposed for the rolling treatment measures.The results show that the comprehensive investiga-tion method from the light and dark,from the surface to the inside,and from the coarse to the fine can well identify the spatial distribution of the whole sand mining area(including explicit type and hidden type).The use of zoning evaluation of geotechnical engineering and zoning treatment can not only effectively utilize the mechanical proper-ties of soil mass in the sand mining area,but also reduce the amount of foundation treatment and save treatment costs.This method provides a reference idea for the construction of similar sand mining areas in the future.