## 4 Digital Mixing and Intelligent Dynamic Control Technology for Cemented Soft Rock Dams  
The mixing of soft sandstone and riverbed sand and gravel in the Jinjigou project encountered problems such as large fluctuations in the clay content and moisture content, uneven aggregate gradation, and large dispersion of the cementitious material strength, which required the timely testing of cementitious material, timely feedback of testing results, and timely adjustment of the mix ratio to ensure quality and prevent potential safety hazards. Figure 6: Cemented sand and gravel and cemented rockfill: (**a**) schematic diagram of the structure of the cemented rockfill dam and (**b**) laying test of the cemented rockfill material. Note: 1 is the first layer of cemented sand and gravel; 2 is the cemented rockfill layer; and 3 is the second layer of cemented sand and gravel. Figure 7: Radar detection results of the cemented rockfill (G–G’ line). To this end, this study proposes technologies such as the rapid measurement of aggregate properties, digital mixing, intelligent control, and strength prediction and developed a digital mixing and intelligent dynamic control platform for cemented dams, as shown in Figure 8.  
The authors proposed a dual-strength and band-controlled mix ratio design method [17]. Despite the variation in the strength of the cementitious material, the overall safety of the dam is not of concern, because the minimum compressive strength is used to determine the dam's cross-section. A digital mixing and intelligent control technology is proposed to optimize real construction and reduce the associated costs while ensuring safety. Instruments for the rapid measurement of moisture content and clay content were developed. According to the rapid determination of aggregate gradation, moisture content, and clay content, as well as the strength prediction model, the amount of cemented material, and the amount of water for mixing can be dynamically and intelligently adjusted to achieve the dynamic optimization and intelligent control of the mix ratio. The specific dynamic control methods are as follows:  
(1) Based on the spatiotemporal Kriging interpolation method [18], a representative sand and gravel quarry was selected for sampling tests to be carried out at the site of the cemented dam project. Through the new non-destructive testing means, non-contact rapid detection and rapid feedback regarding aggregate gradation, water content, and clay content, as well as rapid adjustment of the mix ratio, were achieved, providing a scientific basis for the real-time monitoring and dynamic control of the mix ratio parameters for construction. Rapid determination of moisture content. Through a comparative study, a microwave moisture monitor [19] was selected as the research object of the rapid monitoring scheme of aggregate moisture, as shown in Figure 9. When the electromagnetic microwave with a specific frequency of 2.4 GHz penetrates the material, the O-H bonds of water molecules in the material absorb the microwave energy at that specific frequency. The moisture content percentage is calculated based on the microwave energy attenuation generated when the  
Figure 8: Digital mixing and intelligent dynamic control platform for cemented dams. microwave penetrates the medium. As the microwave completely penetrates the material during processing, the surface moisture and internal moisture of the aggregates are quickly determined to realize the rapid measurement of the moisture content. Rapid determination of clay content. The principle for the rapid detection of clay content is to examine the difference in resistivity between sand grains and fine grains such as clay, silt, and fines attached to them and then, using purified water or tap water as the medium (preferably purified water), to indirectly measure the clay content in the sand by comparing the electrical resistances of the test samples and standard samples under the same conditions.