Mechanical behaviour of a sprayed concrete lining isolated by a sprayed waterproofing membrane

Nakashima, Masanari; Hammer, Anna-Lena; Thewes, Markus; Elshafie, Mohammed; Soga, Kenichi

doi:10.1016/j.tust.2015.01.004

Cited by 27 publications

(12 citation statements)

References 2 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Recent reported testing of membranes for waterproof SCL (Su et al 2013;Su and Bloodworth 2014;Nakashima et al 2015) have not included the moisture condition and moisture properties of the constituent materials in the lining. Testing of moisture properties of membrane and concrete materials have yet to be included in guidance for design and testing of spray applied membranes.…”

Section: Moisture Properties Of Lining Materialsmentioning

confidence: 99%

Performance of EVA-Based Membranes for SCL in Hard Rock

Holter

2015

Rock Mech Rock Eng

View full text Add to dashboard Cite

The bonded property of multi-layered sprayed concrete tunnel linings (SCL) waterproofed with sprayed membranes means that the constituent materials will be exposed to the groundwater without any draining or mechanically separating measures. Moisture properties of the sprayed concrete and membrane materials are therefore important in order to establish the system properties of such linings. Ethyl-vinyl-acetate based sprayed membranes exhibit high water absorption potential under direct exposure to water, but are found to be significantly less hygroscopic and exhibit lower sorptivity (water absorption rate) than sprayed concrete. This material behavior explains the relatively dry in situ condition of the membrane that was observed. Measured in situ moisture content levels of the membrane material in tunnel linings have been found to vary within the range of 30-40 % of the maximum water absorption potential, and show a decreasing trend over the first 4 years after construction has been completed. A model for the mechanical loading, moisture condition and thermal exposure of the membrane and the resulting realistic parameters to be tested is presented. Laboratory testing methods for the membrane materials are evaluated considering possible loads, moisture and freezing exposure. Material testing of membrane materials was conducted with preconditioning to realistic moisture contents and under different temperature conditions including relevant freezing temperatures for tunnel linings. The main effects of the in situ moisture condition of the tested membrane materials are favorable tensile strengths in the range of 1.1-1.5 MPa and low risk of freeze-thaw damage. The crack bridging capacity of the tested membranes is found to be sensitive to temperature. With membrane thicknesses in the range of 3-4 mm, crack bridging capacity up to 4-6 mm opening of the crack width at 23°C and approximately 1 mm opening at -3°C was measured for the tested membranes. No significant reduction of the tensile bond strength could be demonstrated after 35 freeze-thaw cycles with -3°C minimum temperature at the membrane location in the lining. Further work is required to verify the performance of the SCL system under exposure to high hydrostatic pressures and the effects of long term mechanical exposure.

show abstract

Section: Moisture Properties Of Lining Materialsmentioning

confidence: 99%

Performance of EVA-Based Membranes for SCL in Hard Rock

Holter

2015

Rock Mech Rock Eng

View full text Add to dashboard Cite

show abstract

“…On the one hand, the polymer film can help meet the impermeability demand of the lining structure; on the other hand, this film exhibits sufficient load-bearing capacity and thus can serve as a shear connection layer. Nakashima et al (2015) conducted compression-bending tests on concrete members containing 3 mm thick EVA polymer-based waterproofing membranes. The results showed that concrete members containing waterproofing membranes behaved in a compound manner, indicating that waterproofing membranes can transfer interfacial normal and tangential interactions.…”

Section: Ec 416 1640mentioning

confidence: 99%

Investigation of a novel hydraulic tunnel composite lining with polyurea coating interlayer

Li,

Zhang,

Liu

et al. 2024

View full text Add to dashboard Cite

PurposeMultilayer composite liner structures are the primary structural form of hydraulic tunnels. However, the bearing mechanism of multilayer composite liners has not been investigated thoroughly. Many existing design schemes do not properly achieve a balance between structural safety, anti-seepage capacity, and cost effectiveness. Thus, a new composite liner structure type and its theoretical model was proposed.Design/methodology/approachA novel hydraulic tunnel composite liner structure with a polyurea spray coating interlayer was proposed in this study. A theoretical model based on the state-space method was developed and verified using FEM models and existing theoretical models. Parametric analysis was conducted based on the theoretical model to investigate the influence of various variables, including interfacial shear stiffness, inner liner thickness, and outer liner elastic modulus.FindingsIt was concluded that the proposed theoretical model can be used successfully to calculate multilayer composite liner structures with high calculation efficiency. The overall deformation stiffness of the composite liner system increased with the interfacial shear stiffness. The sprayed coating interlayer significantly affects the residual force distribution between the outer and inner liners, which can also be affected by the adjustment of the thickness of the outer and inner liners. Thus, attention should be paid to these factors in the rational design of the proposed composite liner system.Originality/valueWith the development of China’s water conservancy projects, complex geological conditions, high surrounding rock stress, high internal and external water pressures, and other unique application scenarios have gradually increased. This places higher requirements on the bearing performance and impermeability of hydraulic tunnel lining structures. On the other hand, conventional hydraulic tunnel lining structures can hardly achieve a satisfactory balance between economy, structural safety, and impermeability. Thus, the proposed structure has the potential to be used in a wide range of applications.

show abstract

“…Values of interface compression and tension stiffness and strength were not proposed. Nakashima et al [57] presented flexural tests on two composite SCL beams (with sandwiched EVA based sprayed membrane) with and without axial force under ambient laboratory conditions. No information is given on mechanical properties of the membrane interface.…”

Section: Wet Dry Partially Saturated)mentioning

confidence: 99%