Review of construction and demolition waste management in China and USA

An evaluation of the recycled aggregate characteristics and the recycled aggregate concrete mechanical properties

Study on the propagation law of tunnel blasting vibration in stratum and blasting vibration reduction technology

To cope with tunnel frost damage, studies on prevention methods are routinely conducted to improve environmental protection and energy saving. Based on field investigations, the main available thermal insulation methods and their application are discussed and analysed in this paper. The results show that passive measures, such as a thermal insulation layer or door, cannot completely avoid frost damage. Construction investment of the electric heat tracing (EHT) system is lower at the early stage, but a large investment in operation and pollution problems are needed in the later period. As renewable, clean and environmentally friendly primary energy, geothermal energy can realize energy-saving and emission-reduction. Furthermore, our research team proposed the optimization design method for tunnel heat insulation and anti-freezing by using geothermal energy and presented the challenges for future applications of the ground-source heat pump (GSHP) system in tunnels. The results regarding energy conservation from this review can provide useful technical support in design, operation and management of tunnels in cold regions.

A state-of-the-art review of sustainable energy based freeze proof technology for cold-region tunnels in China

Statistical analysis of fire accidents in Chinese highway tunnels 2000–2016

Postconstruction settlement that occurs before a tunnel is in operation may significantly influence the tunnel’s long-term stability. The current study investigates such a tunnel, a three-l...

Investigating the Long-Term Settlement of a Tunnel Built over Improved Loessial Foundation Soil Using Jet Grouting Technique

This short communication gives a brief investigation of the catastrophic natural landslides in the Diexi town, Maoxian County, Sichuan province, SW China, which occurred on June 24, 2017. According to the preliminary statistics of Sichuan government, about 73 people lost contact, and 62 houses and more than 1600 m roads were buried. The collapse volume of landslide is approximately 8 million m3. The maximum drop is about 1600 m, and plane sliding distance is 2500–3000 m. Unfortunately, the secondary collapse incident occurred repeatedly on June 25 and 27, respectively. In this communication, the accident background, accident scene, and related emergency response are presented. In virtue of the in situ reconnaissance conducted by geological experts, the main reason for the collapse is the high-level and long-distance debris flow in earthquake fracture zone induced by continuous rainfall.

The catastrophic landside in Maoxian County, Sichuan, SW China, on June 24, 2017

Cement fly ash gravel (CFG) pile composite foundation is an effective and economic foundation treatment approach, which is significant to building foundation, subgrade construction, and so forth. The present paper aims at investigating the settlement behaviors of saturated tailings dam soft ground under CFG pile composite foundation treatment, in which FEM and laboratory model test were utilized. The proposed findings demonstrate that CFG pile treatment is effective in reinforcing saturated tailings dam and loading has little influence on settlement of soil between piles. The variation of soil between piles settlement in FEM has a good agreement with the laboratory model test. Additionally, the cushion deformation modulus has a small effect on the composite foundation settlement, although the cushion thickness will generate certain influence on the settlement distribution of the composite foundation.

/pdf/settlement-analysis-of-saturated-tailings-dam-treated-by-cfg-3svv0i3p78.pdf

Settlement Analysis of Saturated Tailings Dam Treated by CFG Pile Composite Foundation

Shield tunneling adjacent to pile groups is always an unavoidable problem in urban metro construction. A case was found in the project of Tianjin Metro Line 7, where a shield tunnel would be constructed near the existing pile groups of Shiyou Bridge. The whole shield tunnel is close to pile groups, and the minimum distance is only 0.8 m. Therefore, four kinds of protective schemes are proposed in this paper. It is vital to select an appropriate protective scheme to guarantee the safety during the tunnel construction. In this study, the main mechanical characteristic and physical parameters of site soil were obtained through laboratory tests. Besides, the three-dimensional finite element method was carried out to compare and analyze the effectiveness of the protective schemes in mitigating the effects of tunneling on adjacent pile groups. The results show that the deep-hole grouting scheme has better control effect on the lateral deformation and bending moment of piles, while the pile foundation underpinning scheme has better effectiveness on reducing the settlement of bridge structure and ground deformation. Finally, the deep-hole grouting reinforcement scheme will be adopted to ensure the shield passing through the pile groups smoothly.

/pdf/a-comparative-study-of-protective-schemes-for-shield-52ki7l9zsz.pdf

A Comparative Study of Protective Schemes for Shield Tunneling Adjacent to Pile Groups

Cement fly-ash gravel (CFG) pile is a widely used ground reinforcement technique. This paper aims to address the mechanical characteristics of CFG composite foundation in consolidating saturated mine tailings (MTs) dam. The field static load tests were employed to explore the bearing capacity of the CFG composite foundation, and finite element (FE) models in three dimensions validated through comparison with experimental results were used to discuss the pile-soil stress distribution and pile-soil stress ratio of the CFG composite foundation. The results indicate that the distribution of earth pressure and pile stress is relatively homogeneous and stable over depth and load, while the development of CFG composite foundation bearing capacity is insufficient, in which the developed bearing capacity of CFG piles is less than 50% of its characteristic value. Additionally, compared with the laboratory model test results, the pile-soil stress ratio decreases with the increasing of the load in FEM results proved to better conform to the actual engineering conditions. Furthermore, the deformation modulus and thickness of cushion exert significant influence on pile-soil stress ratio and integral bearing capacity of CFG composite foundation.

/pdf/stress-analysis-of-cfg-pile-composite-foundation-in-17lo02cyc3.pdf

Liu Houquan

Papers

Investigating the Long-Term Settlement of a Tunnel Built over Improved Loessial Foundation Soil Using Jet Grouting Technique

The catastrophic landside in Maoxian County, Sichuan, SW China, on June 24, 2017

Settlement Analysis of Saturated Tailings Dam Treated by CFG Pile Composite Foundation

A Comparative Study of Protective Schemes for Shield Tunneling Adjacent to Pile Groups

Stress Analysis of CFG Pile Composite Foundation in Consolidating Saturated Mine Tailings Dam