To meet the ultra-high bearing capacity design requirements of pile foundations under geological conditions without a good holding layer, we invented a new type of group pile foundation with the soil continuously solidified between piles (hereinafter referred to as the SCS group pile foundation). Considering the solidified depth as a key influencing factor, the vertical ultimate compressive bearing capacity, load transfer law, and damage pattern of the soil around the continuously solidified group pile foundation were investigated using an indoor half-model test. The results revealed that the setting of the continuously solidified part has a significant effect on its compressive bearing characteristics. The ultimate compressive bearing capacity of the SCS group pile foundation was increased by four to nine times compared with the traditional group pile foundation. When the pile spacing is 4–6D (D = pile diameter), designing a continuously solidified depth greater than 14D is recommended. Except for the solidified depths of 2D and 18D, the lateral resistances of the other model piles first increase and then decrease with increasing depth. The maximum values were located at the continuously solidified part and were obviously larger than those of the other pile sections. The maximum pile lateral frictional resistance was provided at the maximum depth of the continuously solidified part. After setting up the continuously solidified part, none of the bearing capacity of the pile ends exceeded 5%. The bearing capacity of the SCS group pile foundation was mainly shared by the continuously solidified part and the pile lateral frictional resistance. For the same pile spacing, the high strain damage zone of the soil at the bottom of the continuously solidified 2D–14D foundation was “abacus bead”; when the burial depth of the continuously solidified part reached 18D, the foundation soil exhibited “inverted bowl” damage.

To solve the problem of the high bearing capacity of structures in deep and weak soil layers, we invented a new type of pile group foundation in which the soil was continuously solidified between piles (hereinafter referred to as the SCS pile group foundation). Considering the two key factors of pile spacing and CSM depth, the antipulling load characteristics of SCS pile group foundations in dry sand were studied via indoor half-model tests and numerical simulations. The results showed that the ultimate uplift capacity of the SCS pile group foundation with a 2D–6D CSM depth was about 2–3 times that of the traditional pile group. When the stiffness of the CSM is so large that its effect can be ignored, the greater the pile spacing is, the greater the ultimate uplift capacity is. For the same pile spacing, the greater the depth of the CSM is, the greater the ultimate uplift bearing capacity is. When the CSM depth is greater than 10D, the uplift effect of the CSM can be effectively exerted, and the antipulling advantage of the SCS pile group foundation can be fully utilized. This study provided a reference for the antipulling design of SCS pile foundations.

Soil nailing is a widely-used technology for retaining cutting works in soil. A significant portion of the cost of construction is related to the construction of a reinforced concrete face. The possibility of replacing the flexible facing with reinforced concrete facing in soil nailing was evaluated by field test. A woven geomembrane was used as a substitute for concrete. In the field test, a slope was made by cutting. During the loading, horizontal displacement and vertical settlement of the slope top, earth pressure of slope top and surface, tension force of woven geomembrane and horizontal displacement of inner slope were observed. The flexible facing performed well, since the facing did not have large vertical and horizontal deformations. The lateral earth pressure on the slope surface was also quite small. When the cutting work was finished, total surcharges of 117.7 kPa was applied on the slope top by six steps and no obvious displacement was observed. Finally, artificial rain fall was conducted on the slope top. After 2 hours’ durations, only shallow surface failure occurred, but the overall slope is stable. Therefore, the flexible facing can replace reinforced concrete in practice. But such kind of improvement should be limited to non-critical structures where large vertical and horizontal deformations are acceptable.

To fully utilize the tensile strength of fiber-reinforced polymer (FRP) bars and prevent shear failure near the anchor head, a new type of adhesive- and pressure-combined steel–plastic composite anchor was designed. Through pull-out tests on 42 new anchor specimens, the effects of the bonding length and crimping pressure on the anchoring performance were studied. The test results showed three typical failure modes of the anchor: pull-out failure, splitting failure, and pull-off failure. Among these, splitting failure best represented the full utilization of the tensile strength of FRP bars and give full play to the bearing capacity of the anchor. Increasing the bonding length of the anchor and applying circumferential normal force crimping could help improve the ultimate bearing capacity of the anchor. Based on the test results, a calculation formula for the ultimate bearing capacity of the anchor in relation to the crimping pressure and the relative anchoring length was proposed. This formula can provide theoretical guidance for the design of new anchors.

In order to enhance the shear strength of mortar - laid through joints in traditional masonry structures and in combination with the development of prefabricated buildings, a new type of prefabricated prestressed masonry structure is proposed. By connecting the through joints with sleeves and wrapping the masonry with geotextiles, and comparing with traditional mortar - laying methods, double - shear tests were carried out on a total of 18 masonry components of six masonry types. The shear - resistance mechanism along the through - joint cross - section and its influencing factors were explored. The test process revealed the shear - resistance performance of the structure and the failure mode of the through - joint cross - section, and clarified the force characteristics and distribution laws. The research shows that the shear strength of the new masonry structure is greatly improved when prestress is applied and wrapping materials are used. At the same time, a calculation formula for the shear strength of this masonry structure is proposed. This research provides a theoretical basis and practical guidance for the design and application of prefabricated prestressed masonry structures.