膨胀性岩体隧洞的设计与施工

Design and Construction of Tunnelsin Swelling Rocks

临汾草峪岭隧洞围岩为二造系弱──中等膨胀性岩体．这类膨胀性岩体的主要特性为：含粘土里50％，浸水后膨胀量2～11％，膨胀压力44～172kPa，初始含水量高，风化速度快，放置洞外48h后就风化崩解，最大特点是当其初始含水量损失超过40％时才产生风化崩解现象．针对此种围岩特性，在隧洞设计施工中采取以下措施，取得了较好效果：（1）光面爆破，短循环开挖，以尽量减少爆破对围岩的破坏作用；（2）快速封闭围岩以保持围岩的初始状态8（3）加强支护以抵抗膨胀压力；（4）加强施工监测；（5）搞好防水排水．

In this paper, the features of the swelling rocks and measures which should be adopted in design and construction of tunnels in the rocks are discussed, in the light of experiences obtained from design and construction of Caoyuling Tunnel in Permian System weak-middle swelling rocks-The main features of the rocks are 50% of clay capacity, 2~ 11 % of expanding capacity of the rocks immersed in water, 44~ 172kPa of expansion pressure, high initial moisture capacity, high weathering velocity and weathering disintegration of the rocks which are put out of tunnels for 48 hours. The pri-mary character of the rocks is that they can emerge the phenomenon of weathering disintegration when their initial moisture capacity lost exceed the limit of 40%. In view of the character, some mea-sures are adopted in design and construction and bring about a better effect. These measures are:(1 ) smooth blasting and excavating in short construction cycle to reduce destructive affect of blasting on surrounding rocks (2) rapidly sealing surrounding rocks to keep the initial state; (3 ) strengthening supports to resist the expansion pressure; (4) strengthening construction monitoring; (5 ) water proof-ing and draining