土石坝下游坝坡填筑料的稳定性分析

朱关震 何芳婵

摘 要：土石坝坝坡土体颗粒之间存在一些间隙，在蓄水之后，会沿着间隙产生一定的不稳定性，如果不稳定性比较大，细颗粒就会被水带出坝体，导致空隙的形成，在水压的作用下，等到空隙达到了一定程度，就会对坝坡的安全性和稳定性造成威胁。某水库工程进行日常巡查时，管理单位发现大坝下游坡面出现有局部塌陷与隆起，初步分析原因可能是下部垫层填料不密实随着时间的推移逐步沉陷引起的。为查明下游坝坡脱空区下部的垫层是否密实，同时查明下游坝坡塌陷、隆起区下部是否有滑动面，确定坝坡隐患是滑动破坏还是冲刷破坏，通过选择部分典型的预制块塌陷、隆起区域，在对护坡表层进行详细测量后，开挖探坑，按照分层取样，进行实地探察，进而进行相关试验及粒径级配分析、填筑料的颗粒分析比对试验，查明了粒径的分布特点，初判降雨水流冲刷是坝坡隐患出现的主要原因。

关键词：土石坝;坝坡;颗粒分析

中图分类号：TV641 文献标识码：A 文章编号：1003-5168（2021）22-0066-04

Abstract： Earth and rockfill dam dam slope has some space between the soil particles， after water storage， can produce certain instability， along the clearance if instability is bigger， fine particles can be hose out of dam body， lead to the formation of the gap， under the action of water pressure， until the gap reached a certain level， will pose a threat to the security and stability of dam slope. During the daily inspection of a reservoir project， the management unit found local collapse and uplift on the downstream slope of the dam， which may be caused by the gradual subsidence over time due to the uncompacted padding of the lower cushion. The purpose of this paper is to find out whether the cushion layer under the downstream dam slope void area is dense， and whether there is sliding surface under the downstream dam slope collapse and uplift area， and determine whether the hidden danger of dam slope is sliding failure or scouring failure. By choosing some typical preform subsidence， uplift area， after a detailed measurements in the surface layer of slope protection， excavation pit， according to the stratified sampling， field exploration， then the relevant test and grain size grading， filling material particle analysis comparison test， find out the distribution characteristics of grain size， initial flow washout for the rainfall is the main reason for the dam slope hazard occurred.

Keywords： earth-rock dam; dam slope; grain size analysis

土石壩泛指由当地土料、石料或混合料，经过抛填、辗压等方法堆筑成的挡水坝[1]。土石坝坝坡土体颗粒之间存在一些间隙，水库在蓄水之后受到水压力的作用，会沿着间隙产生一定的不稳定性，在背水坡可能会有出逸点形成。如果不稳定性比较大，细颗粒就会被水带出坝体形成空隙，时间一久就会导致不稳定性通道形成，空隙变大，渗流量和不稳定性也就不断增大。……