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本書主要對砂卵石地層公路隧道設計及施工關鍵技術講解，主要包括：砂卵石地層與隧道結構相互作用機理，砂卵石地層隧道設計關鍵技術，砂卵石地層隧道施工關鍵技術。將為砂卵石地層隧道的精細化設計、施工和維修養(yǎng)護，提供重要的參考依據(jù)和指導，具有重要理論意義和工程實用價值，應用前景廣闊。

　　China is mountainous and streamy， with a wide range of thick-bedded or huge thick-bedded sandy gravel strata alluviated， accumulated or deposited on the edges of mountains and rivers， bank slopes or terraces.Such sandy gravel strata are widely distributed in Chengdu， Beijing，Changsha， Gansu and other areas. Now， an increasing number of highways and high-speed railway tunnels are built in sandy gravel strata. To ensure the smoothness， safety and comfort of space curves of roads， tunnel is usually the first choice when the strata are unsteady sandy gravel.
　　Many tunnels crossing through sand-pebble stratum road have been built between the highway from Weiyuan County to Wudu District of Gansu Province， such as Dangchang Tunnel (300m of cobble stone layer; the length is the total length of the left and the right caves， the same below) ，Guan'egou Tunnel (280m of cobble stone layer) ， Shawan Tunnel (520m
　　of cobble stone layer) ， Baiheqiao Tunnel ( 1， 114m of cobble stone layer) ，Xiaoshanping Tunnel (720m of cobble stone layer) ， etc. The petrofabric of the surrounding rock of sand pebble is complex under microscopic observation， composed of granules consisting of sand and cobble granules.The shape of cobble is mainly oval or sub-round; the granules contact each other by points; the granule motion is independent to each other， Thus，the temporary pressure arch formed by the surrounding rock of sand pebble
　　is very unsteady， and the strata of sand pebble have prominent problems of looseness， easy collapse， losing steadiness when encountering water， etc.
　　This book mainly discusses the computing method of surrounding rock load of sand-pebble strata road， the stress characteristic of tunnel double-lining structure， tunnel construction method， preceding reinforcement and other aspects， and aims to provide theoretic and technologic supports for similar tunnel projects.
　　The book is the summary and extraction of the research findings of the author in many years， including 4 chapters in total. Chapter 1 is introduction; chapter 2 is the macroscopic and microscopic mechanical properties of sand-pebble surrounding rock of tunnels; chapter 3 is about the deformation failure characteristics of road-tunnel surrounding rock in sand-pebble strata;'chapter 4 is about the interaction mechanism of sand-pebble-tunnel surrounding rock and supporting structures.
　　The book is based on the research achievements of the key design andconstruction technologies of sand-pebble strata road tunnel in recent years.Zhang Chunwei， Tian Shixiong， Zhang Zhao and others have contributed a lot for the writing of the book， and acknowledgements are extended to them. The book also referred to existing literatures， books， norms，subjective reports， etc.， and hereby I extend our thanks to relevant contributors. Although the authors have worked hard for the book， errors may be unavoidable due to limited scholarly attainments. I sincerely hope readers can oblige me with valuable comments.

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