A critical review on the performance of yielding supports in squeezing tunnels

A literature review on properties and applications of grouts for shield tunnel

Foam concrete (FC) has the potential of being an alternative to ordinary concrete, as it reduces dead loads on the structure and foundation, contributes to energy conservation, and lowers the cost of production and labor cost during the construction and transportation. The paper reports a state-of-the-art review of foam concrete in terms of its components, manufacturing and material properties like drying shrinkage, compressive strength, stability and pore structure, etc. In view of the significance of the FC in engineering construction, it also includes a state-of-the-practice review of foam concrete in tunnel and underground engineering. Some shortcomings and technical limitations as well as emerging direction for performance enhancement of FC are also discussed. Current review concludes that the long-term performance and enhancement-associated properties need to be deeply investigated. This study can help alleviate consumer concerns and further encourage the wider application of FC in civil engineering.

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Foam Concrete: A State-of-the-Art and State-of-the-Practice Review

Most geotextiles consist of polymers of polyolefin, polyester or polyamide family, which involve environmental problems related to soil pollution. Geotextiles can be used for at least one of the following functions: Separation, reinforcement, filtration, drainage, stabilization, barrier, and erosion protection. Due to the characteristics of high strength, low cost, and easy to use, geotextiles are widely used in geotechnical engineering such as soft foundation reinforcement, slope protection, and drainage system. This paper reviews composition and function of geotextiles in geotechnical engineering. In addition, based on literatures including the most recent data, the discussion turns to recent development of geotextiles, with emphasis on green geotextiles, intelligent geotextiles, and high-performance geotextiles. The present situation of these new geotextiles and their application in geotechnical engineering are reviewed.

Review of Application and Innovation of Geotextiles in Geotechnical Engineering.

In face of the complicated and changing geological conditions, safety issue is always a primary concern during the construction phase of tunnel in the mountainous regions of China. This Express Let...

Geohazards, reflection and challenges in Mountain tunnel construction of China: a data collection from 2002 to 2018

As a typical granular bulk medium, problems are common in boulder-cobble mixed grounds, such as easy collapse and instability and difficult effective support for large-section tunnel excavation. Tunnels constructed in BCM grounds are rare still, and there is a big gap between the design and construction of tunnels. Based on the Nianggaicun highway tunnel crossing the BCM grounds, the construction technology of tunnel in BCM grounds is studied by means of literature investigation and field survey. Here are the main conclusions: the overall deformation of surrounding rock is quite small; the pressure distribution of surrounding rock is small and loose pressure is dominant, and the safety reserve of secondary lining is large. The deformation process of surrounding rock concentrates on the construction stage. During the construction process, there are many problems, such as serious overexcavation, difficulty of bolt penetration, and continuous rock fall. In this paper, a three-bench complementary cyclic excavation method is proposed, which replaces the original CD and CRD methods. Meanwhile, the supporting system is optimized. The results show that the disturbance of surrounding rock is reduced, while the safety of construction process and the reliability of structure are increased. The new excavation method and optimized supporting system are expected to fill the gap between design and construction of tunnel in BCM grounds and provide reference for construction of such tunnels in the future.

Li Chenghan

Papers

Review of Application and Innovation of Geotextiles in Geotechnical Engineering.

New Construction Technology of a Shallow Tunnel in Boulder-Cobble Mixed Grounds