Chapter 6 The main engineering geology problems in civil engineering 第六章 工程地质问题分析

The main topics of chapter 6: §6-1 The erosion of river( 河流的侵蚀 ) §6-2 landslide （滑坡） §6-3 Collapse （崩塌） §6-4 mudflow （泥石流） §6-5 Karst and Earth cave （岩溶和土洞） §6-6 The engineering problems in underground engineering （地下工程地质问题）

§6-1 The erosion of river( 河流的侵蚀 ) 一、 What is river erosion Which mean the damage to the river bed or river bank, the river erosion is the most active,vigorous factor to the change of topography. No river erosion, no complicated surface. 二、 The river erosion ’ s type Which can be divided into ： side erosive （侧蚀） cut erosion （下蚀）

cut erosion( 下蚀 ) → means that the moving water and its materials carried by water have motive power that makes river bed deepened continuously.Cut erosion are usually obvious in upstream of river. In bridge engineering, the location of foundation must be considered carefully. That is the elevation of bottom surface of foundation must will be lower than the erosion base line( 侵蚀基准面 ).

Erosion line 1 Erosion line 2

side erosive Side erosion are caused by traverse circulation of river. The results of side erosion is that river valley is broaden. The side erosion is obvious in middle or downstream of river. Preventing method: stone cage, changing of river route

Direction of side erosion Building is not in good position traverse circulation of river

§6-2 landslide （滑坡） 一.The definition of landslide （滑坡的定义） The soil or rock body slide down along the fixed sliding surface on the action of gravity. The happening of landslide may cause the damage of building, endanger human life, also cause the artifical earthquake.

滑坡形态描述 滑坡体 Sliding body 滑坡床 Sliding bed 滑坡壁 cliff 滑坡面 Sliding surface 扇形张裂缝 Fan-haped tensive cracks 滑坡舌 鼓胀 裂缝 Swelling cracks 剪裂缝 Shear cracks 滑坡周界 滑坡 台阶 二.The feature of different part of landslide Tension cracks

三.The classification of landslide （滑坡分类） 1. According to the materials difference of sliding body （按物质组成分类） ■ soil land sliding 土体滑坡 ■ rock land sliding(bedrock landslide) 岩层滑坡 ■ special landslides( frozen and thaw 、 collape slide) 特殊滑坡

■ soil land sliding( 土体滑坡 ) cohesive soils landslides （粘土滑坡） loess landslides （黄土滑坡） eluvial soils landslides （残积层滑坡） Eluvial soil landslide

cohesive soils landslides

■ rock land sliding(bedrock landslide) 岩层滑坡 顺层滑坡 切层滑坡 滑动面

movement parallel to planes of eakness and occasionally parallel to slope.

■ special landslides( frozen and thaw 、 collape slide) 特殊滑坡 冻融层

Flow: viscous to fluid-like motion of debris.

2 According to the mechanics condition （按滑坡形成的力学条件） River erosion Artificial cutting tractive style Pushing style 3 其它分类方法

四、 the developing process of landslide （滑坡的阶段） step 1 creep deformation stage （蠕动阶段） no fixed sliding plane Soft rock

深层蠕动 表层蠕动

step 2 failure stage （破坏阶段） The penetrating failure plane has formed; the sliding mass slowly or quickly slides along the crack plane ， drunken-like trees; sabre-like trees develops in this stage

step 3 stable stage （稳定阶段） The sliding mass has been in balanced position drunken trees have become to grow vertically

五、 The mechanics analysis and influencing factor

土层均匀时：

六 The analysis influence factors of sliding （滑坡影响因素分析） The influence factor can be considered as the factors which have the contribution to the change of safety factor (K) ① slope appearance （斜坡的几何特征） slop high 坡高 ; slope angle, slope shape ② rock and soils properties （滑坡体岩土性质） soft rock (shale, sand rock) soil with montmorillonite which is easy to absorb water and expanding. ③ structure （结构面发育程度） the condition of strata plane, joint, fault, (dip angle, dip direction)

④ water （地下水和地表水） to soft rock and soil ⑤ earthquakes （地震） to stimulate the liquefaction( 液化 ) to produce the inertia force to rock or soil body ⑥ artificial factors （人为因素） cutting slope impropely putting on (piling) (over lapping) soil or building structure

七、 the control (harness) of land slipping Control principle( 防治原则 ) first prevention ; second harness The controlling measure （方法） ◆ Discharging water (surface water and ground water

Landslide ground Water Drainage Works

◆ the supporting structure Retaining wall Anti-sliding

Deep foundation works would be enforced according to the thrust of the landslide and depth of the sliding surface under such conditions that ordinary piles would not work well enough. In the Kamenose area, these works have been carried out mainly with ferroconcrete piles of 3.5x4.0 meters in diameter and 30x60 meters in length. At present, the works are enforced with larger structures of 6.5 meters in diameter and 100 meters in length.

◆ anchoring bar(pin, rod)

Prestressed Anchors

Anchored Walls for Landslides

◆ unloading and cutting

挡土墙 抗滑桩 锚固工程