Related Experiment Video
Updated: Jun 11, 2025
06:55
Kinematic History of a Salient-recess Junction Explored through a Combined Approach of Field Data and Analog Sandbox Modeling
Published on: August 5, 2016
8.2K
Research on Vault Settlement during Three-Step Tunnel Construction Process Based on Sandstone Rheological Experiment
Chang Peng1, Yong Qu1, Helin Fu2
1China Construction Fifth Engineering Bureau Civil Engineering Co., Ltd., Changsha 410011, China.
Materials (Basel, Switzerland)
|September 28, 2024
Summary
Tunnel stability depends on rock rheology. This study analyzed siltstone and sandstone, finding that rock strength and inverted arch closure distance significantly impact tunnel vault displacement, crucial for high-speed railway projects.
Area of Science:
- Geotechnical Engineering
- Rock Mechanics
- Civil Engineering
Background:
- Tunnel stability is critical for infrastructure projects like high-speed railways.
- The rheological properties of surrounding rock significantly influence tunnel stability.
- Understanding time-dependent deformation is essential for safe tunnel design.
Purpose of the Study:
- To investigate the rheological characteristics of siltstone and sandstone.
- To analyze the impact of rheological parameters on tunnel deformation and stress.
- To determine optimal inverted arch closure distances for high-speed railway tunnels.
Main Methods:
- Laboratory testing to derive rheological curves and parameters for siltstone and sandstone.
- Theoretical analysis of time-dependent deformation mechanisms.
- Numerical simulation using derived parameters to model tunnel behavior.
Main Results:
- Sandstone rheology was modeled using the Cvisc model.
- Maxwell elastic modulus increased with load, while viscous coefficient decreased in sandstone.
- Vault displacement was directly correlated with reduced surrounding rock strength and increased inverted arch closure distance.
Conclusions:
- Rock rheology, particularly strength, is a key factor in tunnel vault displacement.
- Optimal inverted arch closure distance is dependent on rock type and strength, especially in sandstone.
- Findings provide critical data for the design and stability analysis of high-speed railway tunnels.
More Related Videos
Related Concept Videos
01:24Design Example: Aggregate Gradation
91
The right type and quality of aggregates are crucial for concrete as they significantly influence its properties, mix proportions, and cost-effectiveness. If different sources are available for sand, the commonly used fine aggregate in concrete, the selection of sand is primarily based on its gradation.
The grading, or particle-size distribution, of sand is determined using sieve analysis, with standard sizes ranging from 150 μm to 10 mm (ASTM No. 100 sieve to 3⁄8 in. sieve). Sand is...
The grading, or particle-size distribution, of sand is determined using sieve analysis, with standard sizes ranging from 150 μm to 10 mm (ASTM No. 100 sieve to 3⁄8 in. sieve). Sand is...
91
01:20Slump Test
176
The slump test is a widely used method to measure the workability of concrete. It employs a 12-inch high truncated cone mold that tapers from eight inches at the base to four inches at the top. Before testing, the mold is securely attached to a flat base and dampened.
Concrete is poured into the mold in three layers to conduct the test. Each layer is compacted 25 times with a steel tamping rod, which has a five-eighths-inch diameter and a rounded end, to ensure even distribution and eliminate...
Concrete is poured into the mold in three layers to conduct the test. Each layer is compacted 25 times with a steel tamping rod, which has a five-eighths-inch diameter and a rounded end, to ensure even distribution and eliminate...
176
01:28Transition Zone
83
The transition zone in concrete is a critical area where aggregate meets cement paste, marked by a distinct porosity and weakness compared to the surrounding material. The adhesion around the aggregates is primarily due to Van Der Waals forces. The voids within this zone influence its robustness; initially, it is less durable than the surrounding bulk mortar due to larger voids. Initially, when concrete is compacted, a higher water-cement ratio near the aggregates leads to the formation of...
83
01:14Testing Water Quality
103
When the quality of water for concrete preparation is uncertain, its impact on the setting time of cement and compressive strength of mortar is assessed by comparison with de-ionized or distilled water benchmarks. American Society for Testing and Materials (ASTM) C1602 requires the setting times to be within 90 minutes of the control, British Standard (BS) 3146:1980 allows a 30-minute variance in the initial setting, while British Standards European Norm (BS EN) 1008 specifies initial setting...
103
01:29Preplaced Aggregate Concrete
93
Preplaced aggregate concrete is ideal for construction environments that are not easily accessible. The process begins by properly wetting the gap-graded coarse aggregates to remove the dirt, then placing it in the form and compacting it. Voids are filled with a mortar mix pumped under pressure through slotted pipes. This mortar typically consists of Portland cement, pozzolan, fine aggregates, water, and a fluidizing aid. The pozzolan helps reduce bleeding and segregation while improving the...
93
01:18Porosity in Cement Paste
117
The porosity of concrete is a measure of the void spaces within its structure. These spaces impact its strength and durability significantly. When water and cement interact, a chemical reaction called hydration creates a semi-solid paste. This paste includes combined water, making up approximately 23% of the cement's dry mass, and gel water, which fills minuscule voids known as gel pores, accounting for about 28% of the cement gel volume.
The balance of water to cement in the mix is...
The balance of water to cement in the mix is...
117