Research on the retaining structures for high‐steep slopes is extremely significant because of its real‐world applications and far‐reaching implications. A flexible geocell‐reinforced ecological retaining wall as a high‐steep slope protection scheme was developed and applied to the slope protection project of the Ji‐Lai Expressway by analyzing the reinforcement mechanism of the geocell used. The lateral displacement and Earth pressure distribution on the flexible ecological retaining wall applied to the high‐steep slope were studied using finite element numerical simulations and verified using field experiments. Results reveal that the wall maximum horizontal displacement is 2/3 H away from the wall toe because of the replacement of the upper part of soil. There is an obvious bucking effect on the active Earth pressure around the stiffened site, and the flexible deformation of the retaining wall helped effectively release some of the Earth pressure. Consequently, the measured value is lower than the theoretical value. Through this case study, it is demonstrated that the flexible ecological retaining wall as a slope protection technology can be successfully applied to steep slopes with a height of more than 15 m. Moreover, it brings significant advantages for protecting the ecological environment and improving the highway landscape.

In order to systematically study and develop a type of gussasphalt (GA) mix with superior performance, namely GA-10; the effect of Qingchuan Rock Asphalt (QRA) and Trinidad Lake asphalt (TLA) on the GA-10 mix was assessed based on the study of composite natural asphalt modified gussasphalt (CNAMGA) binder. Various analytical tests were used to evaluate the engineering properties, thermal stability and microstructure of CNAMGA mix. The results indicate that the stability of QRA modified binder and TLA modified binder in the normal temperature range and the high temperature range have been improved, and the temperature susceptibility is reduced. The optimal asphalt–aggregate ratio of the GA mix is determined to be 9.7%, which has good high-temperature stability, low-temperature crack resistance and construction workability. The QRA mix has better high-temperature stability than the TLA mix, whereas the low-temperature cracking resistance of the TLA mix is better than that of the QRA mix. The two kinds of GA-10 mix have similar construction workability. The fact that the abundant fine aggregates wrapped in binder fill the coarse aggregates surface contributes to the better adhesion of the GA asphalt concrete. The distribution of aggregate and binder is relatively uniform with fewer pores, and the overall proportion of the binder is greater than that of aggregate.

The silt in the Yellow River alluvial plain typically features low strength and poor water stability, and, thus, alluvial silt treatment needs an amount of cement to improve soil performance. The development of an alternative to reduce or replace the use of cement in soil stabilization has been a hot topic research for a long time. This paper develops an industrial-solid-waste (ISW) curing agent using a response surface methodology, which is a novel composite material made of steel slag, mineral slag, and two desulfurization products; its feasibility on improved silt is expected to be studied systematically. The comparative tests of ISW- and cement-improved silt were conducted to analyze performance and action mechanism. Variance and multiple regression analysis were used to study the effect of factors on responses statistically, and check the significance and correlation of the suggested models. Finally, the in-service performance of ISW-improved silt was evaluated through in-situ tests. Results show that ISW-improved silt can present good mechanical properties and durability, but is much weaker than cement-improved silt in the early curing stage. The strength enhancement amplitude of ISW-improved silt between curing ages of 7 days to 28 days is larger than that of cement-improved silt. The correlation between factors and responses is established with good agreement. Synergisms in the ISW curing agent are stimulated in the alkaline environment, and are conductive to connect the silt particles. The in-service performance of ISW-improved silt showed little difference to that of cement-improved silt; both of them meet the requirements from the perspective of in-situ application. Moreover, the unit cost of an ISW curing agent is less than 1/5 of that of cement. ISW-improved silt has advantages of cost saving, resource recycling and environmental protection.

The advantageous thermal stability and construction workability of gussasphalt, a type of asphalt concrete, has drawn increasing attention. To prepare a type of superior gussasphalt concrete using Qingchuan rock asphalt (QRA), a modified gussasphalt binder was prepared with modifiers made up by different dose of styrene-butadiene-styrene, terpene resin, furfural extraction oil and SAW. Then, the rheological properties, microstructure, and thermal stability of gussasphalt binder were studied. The results indicated that the modifier #1 had significant effects on the other indexes but for the ductility, it was less effective in improving the low-temperature performance of the asphalt binder. The low-temperature performance of the binder with modifier #2 was superior compared with that of binder with modifier #1. The binder with 12.5% QRA and 5% modifier #2 can be regarded as an optimal collocation, which had a superior compatibility, high-temperature performance, and comprehensive temperature susceptibility.