A novel karst cave filling material with shield waste
muck is developed to realize in-situ recycling of shield waste sandy
clay. Herein, a case study is conducted on the Shenzhen metro line 3, and the
shield tunneling-produced sandy clay is taken as raw
material, supplemented with cement and additives, to prepared filling materials
for karst caves under the tunnel. Additionally, the effects of various
additives, water-to-binder
ratios, and clay-to-binder
ratios on the performance of the novel material are examined through indoor
experiments. The coagulation state and practical performance of the prepared
filling materials are further analyzed using scanning electron microscopy and
field tests. The research results indicate the following: (1) Aluminum-calcium oxide-based additives significantly
improve the strength of the filling material, achieving a 1-hour forming strength of 0.479 MPa and a 28-day
strength of 11.048 MPa. Such additives also enhance the water stability and
shrinkage resistance of the material, with a 20.5% increase in the water
stability coefficient and a 63.4% reduction in shrinkage value at 28 days. (2)
Increasing the clay-to-binder
ratio and decreasing the water-to-binder ratio enhance the unconfined compressive strength of the
filling material at 28 days. The strength of the filling material significantly
increases with the rise in the clay-to-binder ratio when the clay-to-binder ratio exceeds 0.3. (3) Scanning electron microscopy tests
reveal that under hydration effect, cement and aluminum-calcium oxide-based additives form fibrous
and flaky connections within the soil, reducing the overall pore volume and
increasing density, resulting in tighter structural connections that yield
higher strength for the filling material. (4) Field application tests of the
filling material are conducted, with an average core sample strength of 4.16
MPa, meeting engineering requirements.
CHEN Zhen
.
Experimental Study on On-Site Preparation of Novel Karst Cave Filler Using Shield Waste Sandy Clay
[J]. Tunnel Construction, 2025
, 45(S1)
: 23
-31
.
DOI: 10.3973/j.issn.2096-4498.2025.S1.003
